WO2020160690A1

WO2020160690A1 - Surface treatments

Info

Publication number: WO2020160690A1
Application number: PCT/CN2019/074735
Authority: WO
Inventors: Yacheng CHUANG; Yong Yong XU; Yong-jun LI; Xiao-jun ZHU
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2019-02-08
Filing date: 2019-02-08
Publication date: 2020-08-13
Anticipated expiration: 2021-08-08

Abstract

A process for treating a surface for a housing for an electronic device. The process comprises i) a first anodizing treatment that comprises anodizing an aluminium-containing surface in the presence of a first acid solution containing ions of a first transition metal to obtain a first anodized surface. The process also comprises ii) a second anodizing treatment that comprises anodizing the first anodized surface with a second acid solution containing ions of a second transition metal to obtain a second anodized surface. The first transition metal is different from the second transition metal.

Description

SURFACE TREATMENTS

BACKGROUND

Aluminium anodizing has been used for finishing aluminium housings for electronic devices such as laptop computers and mobile telecommunications devices such as tablet devices and mobile telephony devices such as smartphones.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flowchart illustrating an example of a process of the present disclosure.

The figure depicts an example of the present disclosure. It should be understood that the present disclosure is not limited to the examples depicted in the figure.

DETAILED DESCRIPTION

As used in the present disclosure, the term “about” is used to provide flexibility to a value or an endpoint of a numerical range. The degree of flexibility of this term can be dictated by the particular variable and is determined based on the associated description herein.

Amounts and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not just the numerical values explicitly recited as the limits of the range, but also to include individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.

As used in the present disclosure, the term “comprises” has an open meaning, which allows other, unspecified features to be present. This term embraces, but is not limited to, the semi-closed term “consisting essentially of” and the closed term “consisting of” . Unless the context indicates otherwise, the term “comprises” may be replaced with either “consisting essentially of” or “consists of” .

It is noted that, as used in this specification and the appended claims, the singular forms “a” , “an” and “the” include plural referents unless the context clearly dictates otherwise.

The present disclosure relates to a process for treating a surface for a housing for an electronic device. The process comprises i) a first anodizing treatment that comprises anodizing an aluminium-containing surface in the presence of a first acid solution containing ions of a first transition metal to obtain a first anodized surface. The process also comprises ii) a second anodizing treatment that comprises anodizing the first anodized surface with a second acid solution containing ions of a second transition metal to obtain a second anodized surface. The first transition metal is different from the second transition metal.

The aluminium-containing surface may be a surface comprising aluminium metal and/or aluminium metal alloy. The surface may be a surface of an aluminium metal substrate or an aluminium alloy substrate. The surface may comprise an aluminium oxide layer prior to the first anodising treatment. This aluminium oxide layer may be formed by surface oxidation on exposure to air. Alternatively, the aluminium oxide layer may be formed by anodising, for example, in an anodising pretreatment as described below.

The present disclosure also relates to a housing for an electronic device. The housing comprises an anodized surface comprising an aluminium oxide layer. The aluminium oxide layer comprises a first transition metal and a second transition metal. The first transition metal differs from said second transition metal.

In some examples, the first transition metal and the second transition metal are incorporated within the aluminium oxide layer.

In some examples, the first transition metal is chromium and the second transition metal is silver.

By anodizing the surface of the housing in the presence of ions of a first transition metal (e.g. chromium ions) , the ions of the first transition metal may be incorporated into the first anodized surface. By anodizing the first anodized surface in the presence of ions of a second transition metal (e.g. silver ions) , the ions of the second transition metal may be incorporated into the second anodized surface. As a result, the treated or anodized surface may comprise ions of the first transition metal (e.g. chromium) and the second transition metal (e.g. silver) . In some examples, the incorporation of these transition metals onto the treated surface of the housing can alter the visual appearance of the surface of the housing. For example, the incorporation of the transition metals (e.g. chromium and silver) may alter the colour and/or shininess of the surface of the housing. In some examples, the relative and total amounts of the first and second transition metals may be varied to alter the visual appearance of the surface of the housing.

. In some examples, the first transition metal and the second transition metal may be incorporated into pores of the anodised aluminium oxide formed as a result of the first anodising treatment and second anodising treatment. In some examples, the transition metals may be incorporated into interstitial sites of the anodised aluminium oxide. In some examples, this can differ from coating or plating processes, whereby a metal film is applied to a pre-existing anodised aluminium oxide layer. In some examples, the transition metals may be incorporated into the anodised aluminium oxide as transition metal ions. In some examples, the transition metal may be incorporated into the anodised aluminium oxide in situ, for example, as the anodised aluminium oxide is being formed during the anodising treatments. In some examples, the transition metals form part of the structure of the aluminium oxide layer. In some examples, the present disclosure relates to a housing obtainable by a process as described in the present disclosure.

In some examples, the first transition metal and/or the second transition metal is selected from a transition metal from Group 6, 10 and/or 11 of the periodic table.

In some examples, the first transition metal and/or the second transition metal is selected from a transition metal from chromium, molybdenum, tungsten, nickel, palladium, platinum, copper, silver and gold.

In some examples, the first transition metal and/or the second transition metal is selected from chromium, silver, copper and nickel.

In some examples, either the first transition metal or the second transition metal is chromium, and the other transition metal is selected from at least one of silver, copper and nickel.

In some examples, the chromium ions are at least one of chromium III and chromium VI ions.

In some examples, before the first anodizing treatment, the surface of the housing for the electronic device is treated by an anodizing pretreatment.

In some examples, at least one of the first acid solution and the second acid solution is a sulfuric acid solution.

In some examples, at least one of the first acid solution and the second acid solution has a transition metal ion concentration in the range of about 10g/l to about 70g/l.

In some examples, the process further comprises at least one further anodizing treatment that comprises anodizing the surface with a further acid solution containing ions of a further metal. The further metal may be a metal other than the first transition metal or the second transition metal.

In some examples, the at least one further anodizing treatment is carried out before or after the first anodizing treatment; or before or after the second anodizing treatment.

First and/or Second Transition Metal

Any suitable transition metal may be employed as the first and/or second transition metal. For example, the first and second transition metal may be independently selected from any of Groups 4 to 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

4, 5, 6, 7, 8, 9, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

4, 5, 6, 7, 9, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

4, 5, 6, 7, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

5, 6, 7, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

6, 7, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

6, 10, 11 or 12 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of

Groups

6, 10 or 11 of the periodic table. In some examples, the first and second transition metal may be independently selected from any of Groups 6 and 11 of the periodic table.

The first and/or second transition metal may be independently selected from titanium (Ti) , zirconium (Zr) , hafnium (Hf) , vanadium (V) , niobium (Nb) , tantalum (Ta) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , manganese (Mn) , rhenium (Re) , iron (Fe) , ruthenium (Ru) , osmium (Os) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and silver (Au) . In some examples, the first and/or second transition metal may be independently selected from titanium (Ti) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the first and/or second transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the first and/or second transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , copper (Cu) and silver (Ag) . In some examples, the first and/or second transition metal may be independently selected from chromium (Cr) , nickel (Ni) , copper (Cu) and silver (Ag) .

The first transition metal may be independently selected from titanium (Ti) , zirconium (Zr) , hafnium (Hf) , vanadium (V) , niobium (Nb) , tantalum (Ta) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , manganese (Mn) , rhenium (Re) , iron (Fe) , ruthenium (Ru) , osmium (Os) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and silver (Au) . In some examples, the first transition metal may be independently selected from titanium (Ti) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the first transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the first transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , copper (Cu) and silver (Ag) . In some examples, the first transition metal may be independently selected from chromium (Cr) , nickel (Ni) , copper (Cu) and silver (Ag) . In some examples, the first transition metal may be chromium (Cr) . In other examples, the first transition metal may be independently selected from nickel (Ni) , copper (Cu) and silver (Ag) , for instance, silver (Ag) .

In some examples, the second transition metal may be independently selected from titanium (Ti) , zirconium (Zr) , hafnium (Hf) , vanadium (V) , niobium (Nb) , tantalum (Ta) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , manganese (Mn) , rhenium (Re) , iron (Fe) , ruthenium (Ru) , osmium (Os) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and silver (Au) . In some examples, the second transition metal may be independently selected from titanium (Ti) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the second transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the second transition metal may be independently selected from chromium (Cr) , molybdenum (Mo) , tungsten (W) , nickel (Ni) , copper (Cu) and silver (Ag) . In some examples, the second transition metal may be independently selected from chromium (Cr) , nickel (Ni) , copper (Cu) and silver (Ag) . In some examples, the second transition metal may be chromium (Cr) . In other examples, the second transition metal may be independently selected from nickel (Ni) , copper (Cu) and silver (Ag) , for instance, silver (Ag) .

In one example, either the first transition metal or the second transition metal is chromium (Cr) , and the other transition metal is selected from at least one of silver (Ag) , copper (Cu) and nickel (Ni) .

In one example, either the first transition metal or the second transition metal is chromium (Cr) , and the other transition metal is selected from at least one of silver (Ag) and nickel (Ni) .

In one example, either the first transition metal or the second transition metal is chromium (Cr) , and the other transition metal is selected from at least one of silver (Ag) and copper (Cu)

In one example, either the first transition metal or the second transition metal is chromium (Cr) , and the other transition metal is selected from silver (Ag) .

In one example, the first transition metal is chromium (Cr) , and the second transition metal is selected from at least one of silver (Ag) , copper (Cu) and nickel (Ni) .

In one example, the first transition metal is chromium (Cr) , and the second transition metal is selected from at least one of silver (Ag) and nickel (Ni) .

In one example, the first transition is chromium (Cr) , and the second transition metal is selected from at least one of silver (Ag) and copper (Cu) .

In one example, the first transition metal is chromium (Cr) , and the second transition metal is selected from silver (Ag) .

In one example, the second transition metal is chromium (Cr) , and the first transition metal is selected from at least one of silver (Ag) , copper (Cu) and nickel (Ni) .

In one example, the second transition metal is chromium (Cr) , and the first transition metal is selected from at least one of silver (Ag) and nickel (Ni) .

In one example, the second transition is chromium (Cr) , and the first transition metal is selected from at least one of silver (Ag) and copper (Cu) .

In one example, the second transition metal is chromium (Cr) , and the first transition metal is selected from silver (Ag) .

Where chromium ions are used, the chromium ions may be at least one of chromium III and chromium VI ions. In some examples, the chromium ions comprise or consist essentially of chromium III ions. In some examples, the chromium ions comprise or consist essentially of chromium VI ions. In some examples, the chromium ions comprise or consist essentially of chromium III ions and chromium VI ions.

In some examples, chromium (e.g. chromium ions) may be incorporated into the first anodized layer during the first anodizing treatment. In some examples, chromium may be incorporated into the aluminium oxide layer formed as the first anodized surface during the first anodizing treatment.

In some examples, silver (e.g. silver ions) may be incorporated into the second anodized layer during the second anodizing treatment. In some examples, silver may be incorporated into the aluminium oxide layer formed as the second anodized surface during the second anodizing treatment.

In some examples, the incorporation of chromium and silver into the anodized layers may alter the visual appearance of the treated surface. For example, the incorporation of chromium and silver into the anodized layers may alter the colour and/or shininess of the treated surface. In some examples, it may be possible to alter the conditions of the first anodizing treatment and/or second anodizing treatment to vary the visual appearance of the surface as required. For example, it may be possible to vary the concentration of chromium and/or silver ions in the first acid solution and/or second acid solution, respectively. It may also be possible to vary the amount or nature of, for example, the chromium ions (e.g. Cr (III) or Cr (VI) in the solution) . Additionally or alternatively, it may be possible to vary the duration of the first and/or second anodizing treatments and/or the voltages applied during anodizing.

The first and/or second transition metal may be dissolved in their respective acid electrolyte solutions in any suitable form. For example, transition metal compounds may be dissolved in the acid electrolyte solutions. Examples of suitable compounds include salts, acids or bases. Examples of suitable salts include inorganic and organic salts. Suitable salts include halides, for example, fluorides, chlorides, bromides and iodides. Hypohalite, halite, halite and perhalate salts may also be suitable. Other examples include nitrates and nitrites; phosphates, phosphonates and phosphites; acetates and sulphates and sulphonates. Complex metal salts may also be employed. Examples include chromate salts.

Where chromium is used, the chromium may be dissolved as Cr (VI) ions. Examples include chromate ions and dichromate ions. Alternatively or additionally, where chromium is used, the chromium may be dissolved as chromium (III) . Suitable chromium (III) compounds include chromium (III) nitrate, chromium (III) acetate and chromium (III) oxide.

Where silver is used, the silver may be dissolved as, for example, silver nitrate.

First and/or Second Acid Solution

At least one of the first acid solution and the second acid solution may have a transition metal ion concentration that is greater than about 1 g/l, for example, greater than about 2 g/l, greater than about 3 g/l., greater than about 5 g/l, greater than about 8 g/l or greater than about 10 g/l. At least one of the first acid solution and the second acid solution may have a transition metal ion concentration that is less than about 500 g/l, for example, less than about 400 g/l, less than about 300 g/l., less than about 200 g/l, or less than about 150 g/l. In some examples, at least one of the first acid solution and the second acid solution may have a transition metal ion concentration in the range of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l. In some examples, the transition metal ion concentration range may be 10g/l to about 70g/l.

In some examples, the first acid solution may have a first transition metal ion concentration of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l. In some examples, the first acid solution may have a first transition metal ion concentration of about 10g/l to about 70g/l. For the avoidance of doubt, the first transition metal may be as described above. In some examples, the first transition metal may be chromium (Cr) . In other examples, the first transition metal may be independently selected from nickel (Ni) , copper (Cu) and silver (Ag) , for instance, silver (Ag) .

In some examples, the second acid solution may have a second transition metal ion concentration of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l. In some examples, the second acid solution may have a second transition metal ion concentration of about 10g/l to about 70g/l. For the avoidance of doubt, the second transition metal may be as described above. In some examples, the second transition metal may be chromium (Cr) . In other examples, the second transition metal may be independently selected from nickel (Ni) , copper (Cu) and silver (Ag) , for instance, silver (Ag) .

In one example, either first acid solution or the second acid solution has a chromium ion concentration of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l or about 10g/l to about 70g/l. The other acid solution may have a silver ion, copper ion or nickel ion concentration in the range of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l or about 10g/l to about 70g/l. In some examples, the other acid solution may have a silver ion concentration of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l or about 10g/l to about 70g/l.

In certain examples, at least one of the first acid solution and the second acid solution is an acid solution in sulfuric acid. In certain examples, at least one of the first acid solution and the second acid solution is a sulfuric acid solution.

The sulfuric acid may be sulfuric acid having a concentration of at least about 50 g/l, for example, at least 80g/l or at least 100 g/l. The sulfuric acid may be sulfuric acid having a concentration of at most about 800 g/l, for example, at most 700g/l or at most 600 g/l. In some examples, the sulfuric acid may have a concentration in the range of about 100g/l to about 500g/l, for example, about 120 g/l to about 450 g/l. In some examples, the sulfuric acid may have a concentration of about 150 g/l to about 300 g/l. In some examples, the sulfuric acid may have a concentration in the range of 195g/l to about 205g/l.

The concentration of sulfuric acid in the first acid solution may be the same or different from the concentration of sulfuric acid in the second acid solution.

As an alternative to sulphuric acid, phosphoric acid, oxalic acid or chromic acid may be employed. In certain examples, sulphuric acid is employed.

The acid in the first acid solution may be the same or different from the acid in the second acid solution. In some examples, the acid in the first acid solution and in the second acid solution may be sulfuric acid.

First and/or Second Anodizing Treatment

The first anodizing treatment and/or the second anodizing treatment may be performed at any suitable temperature. In certain examples, at least one of the first anodizing treatment and the second anodizing treatment is carried out at a temperature of at least about 5℃, for example, at least about 10℃. In some examples, at least one of the first anodizing treatment and the second anodizing treatment is carried out at a temperature of at most about 80℃, for example, at most about 70℃ or at most about 60℃. In some examples, at least one of the first anodizing treatment and the second anodizing treatment is carried out at a temperature of about 10 to about 40℃, for example, about 15 to about 25℃.

The first anodizing treatment and the second anodizing treatment may be carried out for any suitable length of time. The time may be adjusted to achieve an anodized layer of, for example, a desired thickness and/or appearance. At least one of the first anodizing treatment and the second anodizing treatment may be carried out for a period of about 2 minutes to about 5 hours, for example, about 5 minutes to about 2 hours. In some examples, at least one of the first anodizing treatment and the second anodizing treatment may be carried out for a period of about 25 to about 30 minutes.

The first anodizing treatment and/or the second anodizing treatment may be carried out at any suitable voltage. Suitable voltages may be at least about 5 V, for example, at least about 8 V or at least about 10 V. Suitable voltages may be at most about 100 V, for example, at most about 80 V. In some examples, suitable voltages may be about 5 V to about 50 V, for example, about 8V to about 30 V or about 10 V to about 20V.

The first anodizing treatment may be carried out at a voltage of about 5 V to about 50 V, for example, about 8V to about 30 V or about 10 V to about 20V. In some examples, the first anodizing treatment may be carried out at a voltage range of about 14V to about 15V.

The second anodizing treatment is carried out at a voltage of about 5V to about 50V, for example, about 8V to about 30V or about 10V to about 20V. In some examples, the second anodizing treatment may be carried out at a voltage range of about 15V to about 16V.

In some examples, the first anodizing treatment may be carried out at a voltage that is the same as the voltage at which the second anodizing treatment may be performed. In some examples, the first anodizing treatment may be carried out at a voltage that is different from the voltage at which the second anodizing treatment may be performed. In some examples, the first anodizing treatment may be carried out at a voltage that is lower than the voltage at which the second anodizing treatment may be performed. In some examples, the first anodizing treatment may be carried out at a voltage that is higher than the voltage at which the second anodizing treatment may be performed.

The first and/or second anodising treatment may be carried out by application of a direct current. In some examples, the first anodising treatment may be carried out under a direct current. In some examples, the second or subsequent anodising treatment may be carried out under a direct current. As an alternative to a direct current, an alternating current or pulsed current may be employed.

The current density of the anodising treatment may be from about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the first anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the second or subsequent anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³ or about 1 to about 1.5 Amp/dm ³.

The first anodising treatment may be used to form an anodised aluminium oxide layer comprising the first transition metal. This anodised aluminium oxide layer may have a thickness of at least about 1 μm, for example, at least about 5 μm. The anodised aluminium oxide layer may have a thickness of at most about 100 μm, for example, at most about 60 μm or at most about 40 μm. In some examples, the anodised aluminium oxide layer may have a thickness of about 1 to 100 μm, for example, about 5 to about 60 μm or about 10 to about 40 μm. In some examples, the thickness may be about 1 to about 30 μm, for example, about 5 to about 20 μm or about 5 to about 10 μm.

The second anodising treatment may be used to form an anodised aluminium oxide layer comprising the second transition metal. This anodised aluminium oxide layer may have a thickness of at least about 0.5 μm, for example, at least about 1 μm. The anodised aluminium oxide layer may have a thickness of at most about 100 μm, for example, at most about 60 μm or at most about 40 μm. In some examples, the anodised aluminium oxide layer may have a thickness of about 0.5 to 100 μm, for example, about 1 to about 60 μm or about 1 to about 40 μm. In some examples, the thickness may be about 2 to about 30 μm, for example, about 5 to about 20 μm or about 4 to about 10 μm.

The total thickness of the anodised aluminium oxide layer may be at least about 6 μm. The anodised aluminium oxide layer may have a thickness of at most about 100 μm, for example, at most about 60 μm or at most about 40 μm. In some examples, the anodised aluminium oxide layer may have a thickness of about 6 to 100 μm, for example, about 10 to about 60 μm or about 15 to about 40 μm.

Anodizing Pretreatment

In some examples, before the first anodizing treatment, the surface of the housing for the electronic device is treated by an anodizing pretreatment. In some examples, this anodizing pretreatment may be used to provide the surface with an aluminium oxide layer. In some examples, the anodizing pretreatment may be used to enhamce any pre-existing aluminium oxide layer on the surface. For example, the surface may comprise aluminium having a protective aluminium oxide layer. This protective aluminium oxide layer may form as a result of surface oxidation on exposure, for example, to air. This protective aluminium oxide layer may be enhanced by the anodizing pretreatment. In some examples, any pre-existing aluminum oxide may be at least partially removed prior to anodizing pretreatment. For example, the uniformity of the aluminium oxide layer may be enhanced by removal of any pre-existing surface aluminium oxide layer by a desmutting process prior to the anodizing preparation process.

Where an anodizing pretreatment is employed, the surface to be anodized may be made an anode of an electrochemical cell. The cathode of the cell may be an inert cathode. Suitable inert cathodes can include carbon, stainless steel and/or nickel. The electrolyte may be any suitable electrolyte, for example, an acid electrolyte. In some examples, the acid electrolyte comprises sulfuric acid.

When a potential difference is applied across the electrodes of the electrochemical cell, an aluminium oxide layer may be deposited on the surface of the anode.

The anodizing pretreatment may be carried out at any suitable voltage. Suitable voltages may be at least about 5 V, for example, at least about 8 V or at least about 10 V. Suitable voltages may be at most about 100 V, for example, at most about 80 V. In some examples, suitable voltages may be about 5 V to about 50 V, for example, about 8V to about 30 V or about 10 V to about 20V.

The anodizing pretreatment may be performed at any suitable temperature. In certain examples, the anodizing pretreatment is carried out at a temperature of at least about 5℃, for example, at least about 10℃. In some examples, anodizing pretreatment is carried out at a temperature of at most about 80℃, for example, at most about 70℃ or at most about 60℃. In some examples, the anodizing pretreatment is carried out at a temperature of about 10 to about 40℃, for example, about 15 to about 25℃.

The anodizing pretreatment may be carried out for any suitable length of time. The time may be adjusted to achieve an anodized layer of, for example, a desired thickness. The anodizing pretreatment may be carried out for a period of about 2 minutes to about 5 hours, for example, about 5 minutes to about 2 hours. In some examples, the anodizing pretreatment may be carried out for a period of about 25 to about 30 minutes.

The anodising pretreatment may be carried out by application of a direct current. In some examples, the first anodising treatment may be carried out under a direct current. In some examples, the second or subsequent anodising treatment may be carried out under a direct current. As an alternative to a direct current, an alternating current or pulsed current may be employed.

The current density of the anodising pretreatment may be from about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the first anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the second or subsequent anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³ or about 1 to about 1.5 Amp/dm ³.

The anodising pretreatment may be used to form an anodised aluminium oxide layer. This anodised aluminium oxide layer may have a thickness of at least about 1 μm. The anodised aluminium oxide layer may have a thickness of at most about 100 μm, for example, at most about 60 μm or at most about 40 μm. In some examples, the anodised aluminium oxide layer may have a thickness of about 1 to 100 μm, for example, about 2 about 60 μm or about 5 to about 40 μm. In some examples, the thickness may be about 2 to about 30 μm, for example, about 3 to about 20 μm or about 4 to about 10 μm.

In some examples, the layer formed in the anodising pretreatment may be devoid of the first transition metal and/or the second transition metal.

Further Anodizing Treatments

In some examples, the process further comprises at least one further anodizing treatment. The further anodizing treatment may comprise anodizing the surface with a further acid solution containing ions of a further metal (e.g. a further transition metal) . The further metal may be a metal other than the first transition metal and/or the second transition metal. In some examples, the further metal may be a metal other than the first transition metal but not the second transition metal. In other examples, the further metal may be a metal other than the second transition metal but not the first transition metal. In yet other examples, the further metal may be a metal other than the first and second transition metals.

In some examples, the further anodizing treatment (s) may be carried out before or after the first anodizing treatment; or before or after the second anodizing treatment.

In certain examples, the present disclosure further includes a third anodizing treatment in which the surface on the housing is anodized with an acid solution of a third transition metal ion. The third transition metal ion may be different from the first transition metal ion and/or the second transition metal ion. In some examples, the third metal may be a metal other than the first transition metal but not the second transition metal. In other examples, the third metal may be a metal other than the second transition metal but not the first transition metal. In yet other examples, the third metal may be a metal other than the first and second transition metals.

The third anodizing treatment may be carried out before or after the first anodizing treatment; or before or after the second anodizing treatment.

In certain examples, the present invention further includes a fourth anodizing treatment in which the surface on the housing is anodized with an acid solution of a fourth transition metal ion. The fourth transition metal ion may be different from the first transition metal ion, the second transition metal ion and/or the third transition metal ion. In some examples, the fourth transition metal ion may be the same as one of first transition metal ion, the second transition metal ion and the third transition metal ion, and different from the remainder of the transition metal ions. In some examples, the fourth transition metal ion may be different from first transition metal ion, the second transition metal ion and the third transition metal ion.

The fourth anodizing treatment may be carried out before or after the first anodizing treatment; or before or after the second anodizing treatment. In some examples, the fourth anodizing treatment may be carried out before or after the third anodizing treatment. In some examples, the fourth anodizing treatment may be carried out after the third anodizing treatment.

Where a third transition metal ion and/or a fourth transition metal ion is employed, the transition metal ion may be independently selected from titanium (Ti) , zirconium (Zr) , hafnium (Hf) , vanadium (V) , niobium (Nb) , tantalum (Ta) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , manganese (Mn) , rhenium (Re) , iron (Fe) , ruthenium (Ru) , osmium (Os) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and silver (Au) . In some examples, the third and/or fourth transition metal may be independently selected from titanium (Ti) , chromium (Cr) , molybdenum (Mo) , tungsten (W) , cobalt (Co) , rhodium (Rh) , iridium (Ir) , nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the third and/or fourth transition metal may be independently selected from nickel (Ni) , palladium (Pd) , platinum (Pt) , copper (Cu) , silver (Ag) and gold (Au) . In some examples, the third and/or fourth transition metal may be independently selected from nickel (Ni) and copper (Cu) . In one example, the third transition metal ion may be nickel. In one example, the fourth transition metal ion may be copper. In other examples, the fourth transition metal ion may be nickel and the third transition metal ion may be copper.

In certain examples, the metal ion of the third anodizing treatment and/or the fourth anodizing treatment is an ion selected from the group consisting of copper ions, nickel ions and chromium ions. Where chromium ions are used in the first or second anodizing treatment, any chromium ions used in the third or fourth anodizing treatment may have a different oxidation state from any chromium ion of the first or second anodizing treatment.

In certain examples, the copper ions are Cu ²⁺ ions.

In certain examples, the nickel ions are Ni ²⁺ ions.

In some examples, the incorporation of metal ions in the third, fourth and/or subsequent anodizing treatments may also vary the appearance of the treated surface.

In one example, the first transition metal ions are chromium ions. The second transition metal ions may be silver ions. Where employed, the third transition metal ions may be copper ions, nickel ions or chromium ions that are of a different oxidation state to the chromium ions used as the first transition metal ions. Where employed, the third transition metal ions may be copper ions, nickel ions or chromium ions that are of a different oxidation state to the chromium ions used as the first transition metal ions..

Where employed, at least one of the third acid solution, the fourth acid solution or subsequent acid solution may have a transition metal ion concentration that is greater than about 1 g/l, for example, greater than about 2 g/l, greater than about 3 g/l., greater than about 5 g/l, greater than about 8 g/l or greater than about 10 g/l. Where employed, at least one of the third acid solution, the fourth acid solution or subsequent acid solution may have a transition metal ion concentration that is less than about 500 g/l, for example, less than about 400 g/l, less than about 300 g/l, less than about 200 g/l, or less than about 150 g/l. In some examples, at least one of the third acid solution, the fourth acid solution and/or subsequent acid solution may have a transition metal ion concentration in the range of about 1 g/l to about 200 g/l, for example, 5 g/l to about 150g/l. In some examples, the transition metal ion concentration range may be 10g/l to about 70g/l.

In certain examples, at least one of the third acid solution, fourth acid solution or subsequent acid solution is an acid solution in sulfuric acid. The sulfuric acid may be sulfuric acid having a concentration of at least about 50 g/l, for example, at least 80g/l or at least 100 g/l. The sulfuric acid may be sulfuric acid having a concentration of at most about 800 g/l, for example, at most 700g/l or at most 600 g/l. In some examples, the sulfuric acid may have a concentration in the range of about 100g/l to about 500g/l, for example, about 120 g/l to about 450 g/l. In some examples, the sulfuric acid may have a concentration of about 150 g/l to about 300 g/l. In some examples, the sulfuric acid may have a concentration in the range of 195g/l to about 205g/l.

The concentration of sulfuric acid in the third acid solution may be the same or different from the concentration of sulfuric acid in the fourth or subsequent acid solution.

The third, fourth or subsequent anodizing treatment may be performed at any suitable temperature. In certain examples, the temperature may be at least about 5℃, for example, at least about 10℃. In some examples, temperature may be at most about 80℃, for example, at most about 70℃ or at most about 60℃. In some examples, the temperature may be about 10 to about 40℃, for example, about 15 to about 25℃.

The third, fourth or subsequent anodizing treatment may be carried out for any suitable length of time. The time may be adjusted to achieve an anodized layer of, for example, a desired thickness and/or appearance. The time may be about 2 minutes to about 5 hours, for example, about 5 minutes to about 2 hours. In some examples, the treatment may be carried out for a period of about 25 to about 30 minutes.

The third, fourth or subsequent anodizing treatments may be carried out at any suitable voltage. Suitable voltages may be at least about 5 V, for example, at least about 8 V or at least about 10 V. Suitable voltages may be at most about 100 V, for example, at most about 80 V. In some examples, suitable voltages may be about 5 V to about 50 V, for example, about 8V to about 30 V or about 10 V to about 20V.

The third, fourth or subsequent anodizing treatments may be carried out by application of a direct current. In some examples, the first anodising treatment may be carried out under a direct current. In some examples, the second or subsequent anodising treatment may be carried out under a direct current. As an alternative to a direct current, an alternating current or pulsed current may be employed.

The current density of the third, fourth or subsequent anodizing treatments may be from about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the first anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³. In some examples, the second or subsequent anodising treatment may be carried out at a current density of about 0.1 Amp/dm ² to about 3 Amp/dm ², for example, about 0.4 Amp/dm ³ to about 2 Amp/dm ³ or about 1 to about 1.5 Amp/dm ³.

The third, fourth or subsequent anodizing treatments may each be used to form an anodised aluminium oxide layer. Each anodised aluminium oxide layer may have a thickness of at least about 0.5 μm, for example, at least about 1 μm. The anodised aluminium oxide layer may have a thickness of at most about 100 μm, for example, at most about 60 μm or at most about 40 μm. In some examples, the anodised aluminium oxide layer may have a thickness of about 0.5 to 100 μm, for example, about 0.5 to about 60 μm or about 1 to about 40 μm.

Once the surface of the housing is treated according to an example of the method of the present disclosure, the surface may be subjected to further treatments, for example, dyeing, sealing and/or surface treatment prior to producing the finished housing.

Housing

In certain examples, the housing for an electronic device may be a housing or case for a computer, such as a laptop and/or other portable computing and communications device. In some examples, the housing for an electronic device may be a housing for a tablet computer and/or smartphone. In some examples, the housing may be formed by casting or pressing. In some examples, the housing may be formed of aluminium. The aluminium may be any suitable form, for example, aluminium metal or aluminium alloy. An example of a suitable alloy may be a magnesium aluminium alloy. The aluminium metal or alloy may have an outer layer or coating of aluminium oxide. This oxide layer may be formed as a result of natural passivation of the aluminium surface when exposed to air. In some examples, the oxide layer may be an anodized oxide layer, for example, formed using the anodizing pretreatment described above.

In the present disclosure, a surface for a housing for an electronic device is treated. The surface may be a surface of a housing of an electronic device. Accordingly, a surface of the housing itself may be treated. The treated surface may be subjected to further processing prior to forming the finished housing. In an alternative example, a surface of a substrate may be treated before the substrate is shaped to form the housing. The surface may form any part of the housing. For example, the surface may form at least part of the base, cover or sidewall of the housing.

As discussed above, the present disclosure also relates to a housing for an electronic device. The housing comprises an anodized surface comprising an aluminium oxide layer, wherein said aluminium oxide layer comprises a first transition metal and a second transition metal. The first transition metal differs from the second transition metal.

In some examples, the first transition metal and the second transition metal may be incorporated within the aluminium oxide layer. In some examples, the aluminium oxide layer comprises a first aluminium oxide layer comprising the first transition metal (e.g. chromium) and a second aluminium oxide layer comprising the second transition metal (e.g. silver) . The first aluminium oxide layer may underlie the second aluminium oxide layer. In some examples, the aluminium oxide layer comprises an anodized aluminium oxide layer comprising the first transition metal and the second transition metal dispersed through the layer.

Examples of the present disclosure relate to a housing for an electronic device comprising a substrate having an aluminium oxide surface including chromium and silver. The housing may comprise a substrate having an aluminium oxide surface including chromium ions and silver ions. In some examples, the housing comprises a substrate that comprises aluminium. For example, the housing may comprise an aluminium substrate. The aluminium substrate may comprise aluminium metal and/or aluminium alloy. The surface of the aluminium substrate may comprise aluminium oxide. In some examples, the aluminium oxide surface is an aluminium oxide layer including chromium and silver. Where an aluminium substrate may be formed of aluminium metal or aluminium alloy, the aluminium substrate may comprise an anodized aluminium oxide layer (s) comprising chromium and silver. In some examples, the aluminium substrate may comprise an anodized aluminium oxide layer comprising a first aluminium oxide layer comprising chromium and a second aluminium oxide layer comprising silver. The first aluminium oxide layer may underlie the second aluminium oxide layer. In some examples, the aluminium substrate may comprise an anodized aluminium oxide layer comprising chromium and silver dispersed through the layer.

The above and other features of the present disclosure will now be described, by way of example, in further detail with reference to the following example.

EXAMPLE

Figure 1 is a flowchart describing an example of a process of the present disclosure. The example process may comprise a series of

pre-treatments

10, 11, 12, 13; a sequence of

anodizing treatments

14, 15, 16, 26, 27 and a series of

post-treatments

17, 18, 19, 20, 21, 22, 23, 24, 25.

The pre-treatments may follow procedures may include degreasing 10, chemical polishing 12 and

desmutting

11, 13 as required.

The anodizing treatments of the example include a anodizing pretreatment 14, Anodizing Stage A, under suitable conditions, to form a layer of aluminium oxide on the aluminium substrate or to increase the thickness of an existing aluminium oxide layer.

The example process may also include anodizing treatments in which ions are included in the anodizing medium. A first anodizing treatment 15, Anodizing Stage B, includes the addition of chromium ions such as chromium (III) oxide, chromium (VI) oxide (chromic anhydride) , chromate or dichromate. A second anodizing treatment 16, Anodizing Stage C, includes the addition of silver ions, conveniently as silver nitrate. The counterions in the resultant surface will be oxide or hydroxide ions.

The post-treatments 17 may also follow procedures which will be familiar to the skilled person and may include finishing treatments such as dyeing 22 and sealing 23, together with degreasing 19 and

desmutting

20, 24 as desired. The post-treatments may also include

conditioning

18, 21 using chemical treatments which enhancing cleaning and drying.

The substrate may also be subjected to rinsing throughout the process. Unless the context otherwise indicates, the rinsing processes are generally carried out in tap water (also known as town water, city water and municipal water) . The water may have been subjected to additional treatments such filtration, ion exchange and other purification techniques as might be appropriate or necessary having regard to the quality of the water supply. Where individual stages of the example process may indicate that the water should comply with certain additional characteristics, such as to pH and conductivity, these are mentioned in the following description.

The example process of the present disclosure for treating a surface on a housing for an electronic device will now be described in further detail.

Surface preparation (stages 10-13)

An aluminium housing substrate was prepared according to a desired shape and configuration for supporting the necessary components of the electronic device. The substrate was degreased 10 using sulfuric acid at a concentration of about 30 g/l and at a temperature of about 55℃ (± 2℃) for a period of two minutes. The degreased substrate was rinsed twice in water for about 10 seconds each followed by a final rinse for 10 seconds in water which was checked to have a pH in the range of about 6.5 to about 9.0.

The degreased and rinsed substrate was then subjected to a first desmutting process 11 to remove any existing surface aluminium oxide. The substrate was immersed in nitric acid having a concentration of about 145 to about 155 g/l at ambient temperature for a period of 30 seconds. The desmutted substrate was then rinsed twice in water for about 10 seconds each followed by a final rinse for 10 seconds in water which was checked to have a pH in the range of about 2.5 to about 8.0.

The rinsed desmutted substrate was then subjected to a chemical polishing (CP) process 12. The CP process comprised a pre-dip by immersion in phosphoric acid (1000g/l ± 100g/l) at ambient temperature for 30 seconds, followed by an immersion in phosphoric acid (1000g/l ± 100g/l) at 80℃ for 30 to 60 seconds. Optionally, sulfuric acid is at a concentration of 200g/l ± 50g/l may be added to the phosphoric acid. During the chemical polishing process, the aluminium concentration in the acid was maintained in the range of about 8g/l or less.

The CP-treated substrate was rinsed with hot water at about 50-60℃ for about ten seconds followed by two further rinses in water for about 10 seconds each and a final rinse for 10 seconds in water which was checked to have a pH in the range of about 2.5 to about 8.0.

The substrate was then treated to a second desmutting process 13 under the same conditions as the first desmutting process, followed by two rinses in water for about 10 seconds each and by a final rinse for 10 seconds in water which was checked to have a pH in the range of about 4.0 to about 8.0.

Anodizing

Anodizing Stage A (14)

The surface-prepared substrate was subjected to an initial anodizing process 14. The substrate was anodized in sulfuric acid under the following conditions:

Sulfuric acid concentration -about 200g/l

Temperature -20℃ (± 5℃)

Duration -1,500-1,800 seconds

Voltage -13.5V

The aluminium concentration was maintained in the range of 0-8g/l. The anodized substrate was then rinsed twice in water at ambient temperature and checked to have a conductivity of less than about 1000μS/cm by immersion for periods of 30 seconds each, followed by rinsing in water checked to have a pH in the range of between about 4.0 and about 8.0 and a conductivity of up to 50μS/cm for about 30 seconds.

Anodizing Stage B (15)

The anodized substrate was subjected to an anodizing process 15 including a source of chromium ions, such as chromium (III) oxide, chromium (VI) oxide (chromic anhydride) , chromate or dichromate, according to the following conditions:

Sulfuric acid concentration -about 200g/l

Chromium ion concentration -up to about 70g/l

Temperature -20℃ (± 5℃)

Duration -1,500-1,800 seconds

Voltage -14.5V

The anodized substrate was rinsed twice in water at ambient temperature by immersion for periods of 30 seconds each, followed by rinsing in water or dilute sulfuric acid, having a pH of between about 4.0 and about 8.0 and a conductivity of less than about 50μS/cm, for about 30 seconds.

Anodizing Stage C (16)

The anodized substrate was subjected to an anodizing process 16 including a source of silver ions, according to the following conditions:

Sulfuric acid concentration -about 200g/l

Silver ion concentration -up to about 70g/l (as silver nitrate)

Temperature -20℃ (± 5℃)

Duration -1,500-1,800 seconds

Voltage -15.5V

The anodized substrate was rinsed twice in plain water at ambient temperature by immersion for periods of 30 seconds each, followed by rinsing in water or dilute sulfuric acid, having a pH of between about 4.0 and about 8.0 and a conductivity of less than about 50μS/cm, for about 30 seconds.

Post-anodizing treatments (17-25)

In this example, the anodized substrate was subjected to a conditioning treatment 18 by repeated treatments with a conditioning composition comprising Sormal 121 (Okuno International Corporation) at a concentration of about 40g/l in an ultrasonic bath at a temperature of about 25℃, for a period of about 3 minutes. The pH of the solution was between about 1.8 and about 3. The conditioning treatment 18 was followed by rinsing twice in water for about 30 seconds.

The conditioning process was repeated under the same conditions as set out above followed by a single water rinsing for about 30 seconds and a subsequent rinsing at a pH of between 4 and 8 in a solution having a conductivity of up to 100μS/cm for 30 seconds.

The substrate was degreased 19 in a detergent solution of ALCLEAN 161 (Okuno International Corporation) at a concentration of about 20g/l and at a temperature of about 50 to about 60℃ for about 45 seconds; followed by an initial rinse in water for about 30 seconds and a final rinse in checked to have a pH of between about 4.0 and about 8.0 and a conductivity of up to 100μS/cm for about 30 seconds.

The substrate was subjected to a further desmutting process 20 using nitric acid at a concentration of 145-155g/l at ambient temperature for about 30 seconds, followed by three rinses by immersion in water at ambient temperature for about thirty seconds each.

The substrate was subjected to a further repeated conditioning 21 in a solution of Sormal 121 under the same conditions as described above, each followed by rinsing twice in water for about 30 seconds.

Example Sealing, Desmutting & Drying

The example substrate was sealed 23, under standard conditions, at an elevated temperature of about 95℃ under mildly acidic conditions (pH 5.2-5.8) for about 40 minutes in a solution having a nickel ion concentration of about 1.5g/l; followed by a rinsing of immersion in a solution of a sealing agent, such as Top Seal DX-500 (anickel acetate type sealing agent of Okuno International Corporation) at a temperature about 95℃ and having a pH of 4 to 8 and a conductivity of up to 100μS/cm for about 30 seconds.

The example substrate was subjected to a final desmutting process 24 by immersion in aqueous nitric acid having a concentration of about 3 to about 5 wt. %at ambient temperature for about 30 seconds; followed by rinsing by immersion in hot water for about 30 seconds and then two final rinses in water controlled to have a conductivity in the range of about 2 to about 30,000μS/cm at about 65℃ to about 75℃ for about 30 seconds; after which the substrate was dried 25 at a temperature of about 60℃ to about 75℃ for about 20 minutes with a flow of air over the surfaces of the substrate.

Example intermediate stages

Additional anodizing stages

In certain examples of the process of the present disclosure,

additional anodizing treatments

26, 27 may be included to vary further the final finish of the housing. The additional stages may include an Anodizing Stage D intermediate Anodizing Stage B and Anodizing Stage C; and/or may include an Anodizing Stage E intermediate Anodizing Stage C and the post-anodizing treatments 17. Where included, Anodizing Stage D and Anodizing Stage E are anodizing treatments comprising metal ions other than the chromium ions of Anodizing Stage B and the silver ions of Anodizing Stage C. In certain examples, the metal ions are selected from copper and nickel ions, typically Cu ²⁺ or Ni ²⁺, and from chromium ions having a different oxidation state from the chromium ion selected in Anodizing Stage B.

Dyeing

In certain examples, the substrate may be additionally subjected to a dyeing 22 prior to sealing. The experimental details of the dyeing process will depend upon the requirements of the dye pigment to be used but which will typically be under mildly acidic conditions at a pH of about 5.2 to about 5.8 at a temperature of about 30℃, followed by rinsing as required.

Surface texturing

In certain examples, prior to sealing, the surface of the substrate may additionally be subjected to a surface texturing, such as bead blasting and hairline brushing. A surface texturing may be carried out prior to, or following, any dyeing.

The processes of the present disclosure provide an aluminium housing for an electronic device which has a novel and attractive appearance. By adjusting the cycle time and/or voltage of the chromium anodizing 15 and the cycle time and/or voltage of the silver anodizing 16, the colour of the final finish can be adjusted.

The structure, and therefore the visual appearance, of the finished housing will vary with upon the voltage and the duration of the chromium and silver anodizing treatments and of any other anodizing treatments. In certain examples of the process of the present disclosure, the duration of the first anodizing treatment 15 may be such as to form a discrete layer of chromium ions on the aluminium oxide surface of the substrate such that the second anodizing treatment will form a discrete layer of silver ions on the chromium ions. Alternatively, the duration of the first anodizing treatment may be such as to incompletely fill pores in the aluminium oxide surface with chromium ions such that deposition of silver ions during the second anodizing treatment 16 results in chromium ions and silver ions sharing or partially sharing pores in the aluminium oxide surface of the substrate. If included,

additional anodizing treatments

26, 27 using additional ions will further vary this structure.

Claims

A process for treating a surface for a housing for an electronic device, the process comprising:

i) a first anodizing treatment that comprises anodizing an aluminium-containing surface in the presence of a first acid electrolyte solution containing ions of a first transition metal to obtain a first anodized surface; and

ii) a second anodizing treatment that comprises anodizing the first anodized surface with a second acid solution containing ions of a second transition metal to obtain a second anodized surface, wherein the first transition metal is different from the second transition metal.
The process as claimed in claim 1, wherein the first transition metal and/or the second transition metal is selected from a transition metal from Group 6, 10 and/or 11 of the periodic table.
The process as claimed in claim 2, wherein the first transition metal and/or the second transition metal is selected from a transition metal from chromium, molybdenum, tungsten, nickel, palladium, platinum, copper, silver and gold.
The process as claimed in claim 3, wherein the first transition metal and/or the second transition metal is selected from chromium, silver, copper and nickel.
The process as claimed in claim 4, wherein the either the first transition metal or the second transition metal is chromium, and the other transition metal is selected from at least one of silver, copper and nickel.
The process as claimed in claim 5, wherein the first transition metal is chromium and the second transition metal is silver.
The process as claimed in claim 5, wherein the chromium ions are at least one of chromium III and chromium VI ions.
The process as claimed in claim 1, wherein, before the first anodizing treatment, the surface of the housing for the electronic device is treated by an anodizing pretreatment.
The process as claimed in claim 1, wherein at least one of the first acid solution and the second acid solution is a sulfuric acid solution.
The process as claimed in claim 1, wherein at least one of the first acid solution and the second acid solution has a transition metal ion concentration in the range of about 10g/l to about 70g/l.
The process as claimed in claim 1, which further comprises at least one further anodizing treatment that comprises anodizing the surface with a further acid solution containing ions of a further metal, wherein the further metal is a metal other than the first transition metal or the second transition metal.
The process as claimed in claim 1, wherein the at least one further anodizing treatment is carried out before or after the first anodizing treatment; or before or after the second anodizing treatment.
A housing for an electronic device, said housing comprising an anodized surface comprising an aluminium oxide layer, wherein said aluminium oxide layer comprises a first transition metal and a second transition metal, and wherein said first transition metal differs from said second transition metal.
The housing as claimed in claim 13, wherein the first transition metal is chromium and wherein the second transition metal is silver.
The housing as claimed in claim 13, wherein the first transition metal and the second transition metal are incorporated within the aluminium oxide layer.