CN102115885B - Oil-free self-lubricating plating technique of aluminum alloy parts - Google Patents

Abstract

A process for oil-free self-lubricating coating treatment of aluminum alloy parts, including pre-plating workpiece pretreatment, copper plating intermediate treatment, self-lubricating wear-resistant coating treatment and post-plating heat treatment, characterized in that: the pre-plating workpiece pretreatment The treatment is to degrease the workpiece in a degreasing solution composed of trisodium phosphate, sodium carbonate, sodium silicate and water. The copper plating intermediate treatment is to perform copper plating on the workpiece in a copper sulfate solution. treatment; the self-lubricating wear-resistant coating treatment is to pass the workpiece, in the composition including nickel salt, reducing agent, complexing agent, buffering agent, stabilizer, friction-reducing phase material MoS ₂ , accelerator and surfactant, etc. The deposition-type coating treatment is carried out in the chemical composite solution; the post-plating heat treatment refers to the 6-hour heat preservation and drying treatment of the plated workpiece in a drying oven at a temperature of 180 ° C.

Description

A process for oil-free self-lubricating coating treatment of aluminum alloy parts

technical field

The invention relates to a surface coating technology, especially a process for oil-free self-lubricating coating treatment of aluminum alloy parts

Background technique

The reliability and service life of aluminum parts are significantly affected by the wear rate. For example, some aluminum alloy parts in sewing machines: the needle bar and the needle bar sleeve are in long-term, relatively high-speed frictional motion, and the nature of the material determines the connection. The wear resistance has certain limitations. In view of the existing technology, surface treatment or surface coating of aluminum parts can be used to improve the wear resistance of the surface area, which is particularly effective in reducing the wear of the friction system surface. the

At present, most of the surface coatings are realized by electroless plating. However, the stability of the solution used in electroless plating is poor, and the maintenance, adjustment and regeneration of the solution are troublesome, and the material cost is relatively high. the

Contents of the invention

The purpose of the present invention is to propose a technology for coating wear-resistant coatings on the surface of aluminum alloy parts undergoing relative frictional motion, and it is hoped that both of them can achieve a long-term working state under self-lubricating state. the

This oil-free self-lubricating coating treatment process for aluminum alloy parts includes pre-plating workpiece pretreatment, copper-plating intermediate treatment, self-lubricating wear-resistant coating treatment and post-plating heat treatment, and is characterized in that:

A, the workpiece pretreatment before plating is that the workpiece is degreased in a degreasing solution made of trisodium phosphate, sodium carbonate, sodium silicate and water, wherein Na ₃ PO ₄ : 30g/L; Sodium carbonate Na ₂ CO ₃ : 25g/L; Sodium silicate Na ₂ SiO ₃ : 8g/L, treatment temperature: 70～75℃, time: 2～5min;

B. The copper plating intermediate treatment is to place the workpiece treated in the A process in a copper sulfate solution prepared by 0.9-1.0mol/L H ₂ SO ₄ and 0.75-0.85mol/L CuSO ₄ ·5H ₂ O Copper plating treatment, the process conditions are: oxidation temperature 20 ~ 25 ℃, current density 1.0 ~ 2.5A/dm ² , oxidation time 30min, use pure copper as the electrode;

C. The self-lubricating wear-resistant coating treatment is to process the workpiece through the B process, including nickel salt, reducing agent, complexing agent, buffering agent, stabilizer, friction-reducing phase material MoS ₂ , accelerator and surface Deposition-type coating treatment is carried out in a chemical compound solution composed of active agents, among which nickel salt is controlled at 40-50g/L, reducing agent sodium hypophosphite is controlled at 9-11g/L, and complexing agent trisodium citrate is controlled at 90-110g/L, the buffer ammonium chloride is controlled at 40-60g/L, the friction-reducing phase material _MoS2 is controlled at 1.5-3g/L, and the surfactant is cetyltrimethylammonium bromide Or Tween-60, the control amount added is 6-7mg/L or 0.40-0.5g/L; the solution temperature during deposition and coating is controlled at 90-95°C, and the pH value of the solution is controlled at 8.5-10;

D. The post-plating heat treatment refers to that the post-plating workpiece is subjected to heat preservation and drying treatment at a temperature of 180° C. for 6 hours in a drying oven. the

According to the above technical scheme, the oil-free self-lubricating coating treatment process for aluminum alloy parts, the treated aluminum alloy workpiece not only makes the hardness value of the aluminum substrate reach Ni-PHV _0.025 151-206 HV _0.025 1002; Ni-P-MoS ₂ HV _0.025 297-441 HV _0.025 1072.

Description of drawings

Fig. 1 implements the electronic image of workpiece after Ni-P coating of the present invention;

Fig. 2 is the schematic diagram of the component analysis chart at spectrogram 1 place in Fig. 1;

Fig. 3 is the schematic diagram of the component analysis chart at spectrogram 2 place in Fig. 1;

Fig. 4 is the schematic diagram of the component analysis chart at spectrogram 3 place in Fig. 1;

Fig. 5 implements the Ni-P-MoS of the present invention ₂ workpiece electron image after coating;

Fig. 6 is the schematic diagram of the component analysis chart at spectrogram 1 place in Fig. 5;

Fig. 7 is the schematic diagram of the component analysis chart at spectrogram 2 place in Fig. 5;

Figures 8 to 11 are the test curves of coating adhesion after Ni-P, Ni-P-MoS ₂ coating treatment and drying.

Detailed ways

Embodiments of the present invention are given below, and the present invention is further described in conjunction with the embodiments. the

The process of carrying out oil-free self-lubricating coating treatment on aluminum alloy parts proposed by the present invention uses surface deposition modification technology to make aluminum alloy workpieces, especially aluminum alloy needle bars and needle bar cover components in sewing machines, not only have Ideal surface hardness, but also can keep the needle bar and needle bar sleeve in self-lubricating working condition for a long time. the

This process of oil-free self-lubricating coating treatment on aluminum alloy parts includes pre-plating workpiece pretreatment, copper-plating intermediate treatment, self-lubricating wear-resistant coating treatment and post-plating heat treatment. in

A, the workpiece pretreatment before plating is that the workpiece is degreased in a degreasing solution made of trisodium phosphate, sodium carbonate, sodium silicate and water, wherein Na ₃ PO ₄ : 30g/L; Sodium carbonate Na ₂ CO ₃ : 25g/L; Sodium silicate Na ₂ SiO ₃ : 8g/L, treatment temperature: 70～75℃, time: 2～5min;

After pretreatment, use HNO ₃ (d=1.42g/cm ³ ): 352mL/L to carry out light-emitting process treatment, and the treatment is carried out at room temperature; time: 1-3min.

B. The copper plating intermediate treatment is to put the workpiece processed by the A process in the copper sulfate solution prepared by 0.9～1.0mol/L H ₂ SO ₄ ; 0.75～0.85mol/L CuSO ₄ 5H ₂ O The anodic oxidation process of copper plating is carried out. The process conditions are as follows: base oxidation temperature 20-25°C, current density 1.0-2.5A/dm ² , oxidation time 30min, pure copper as the electrode; The solution used for the anodic oxidation treatment is the same, the current density of the copper electroplating is 0.2-1.0A/dm ² , and the copper plating time is 40 minutes.

The above-mentioned copper plating intermediate treatment can be carried out with an electroplating copper plating solution. At this time, the current density of the electroplating copper is 0.2-1.0 A/dm ² , and the copper plating time is 40 minutes.

C. The self-lubricating wear-resistant coating treatment is to process the workpiece through the B process, including nickel salt, reducing agent, complexing agent, buffering agent, stabilizer, friction-reducing phase material MoS ₂ , accelerator and surface Deposition-type coating treatment is carried out in a chemical compound solution composed of active agents, among which nickel salt is controlled at 40-50g/L, reducing agent sodium hypophosphite is controlled at 9-11g/L, and complexing agent trisodium citrate is controlled at 90-110g/L, the buffer ammonium chloride is controlled at 40-60g/L, the friction-reducing phase material _MoS2 is controlled at 1.5-3g/L, and the surfactant is cetyltrimethylammonium bromide Or Tween-60, the added control amount is 6-7mg/L or 0.40-0.5g/L. The temperature of the solution during deposition and coating is controlled at 90-95°C, and the pH value of the solution is controlled at 8.5-10;

The nickel salt used is the main salt in the plating solution to provide nickel ions, and nickel chloride or nickel sulfate is used. Increasing the concentration of nickel salt will increase the deposition rate, but the stability of the plating solution will decrease. Generally, it should be controlled at 40-50g/L. the

The reducing agent used is sodium hypophosphite as the reducing agent, and sodium hypophosphite is low in price and good in stability of the plating solution. The content of the reducing agent depends on the concentration of the main salt. As the content increases, the deposition rate will also increase, but the stability of the plating solution will decrease, and precipitation will easily occur, which will affect the quality of the coating, which should be controlled at 9-11g/L. the

The complexing agent used is the most important component in the plating solution except the main salt and the reducing agent. In order to avoid the decomposition of the plating solution, a complexing agent must be added to the plating solution. The role of the complexing agent in the plating solution is to form a stable complex with nickel ions, control the concentration of nickel ions participating in the reaction, prevent the precipitation of the plating solution, increase the stability of the plating solution and prolong the service life; at the same time, it can also inhibit Nickel phosphite precipitates, stabilizes the plating solution, and controls the deposition rate; the complexing agent used in this technical solution is trisodium citrate, and the dosage is 90-110g/L. the

The buffering agent used is ammonium chloride. The addition of the buffering agent can make the plating solution have buffering capacity and effectively control the pH of the plating solution. When the pH value is less than 4, the deposition rate is low. When the pH value is greater than 6.5, it is easy to produce micro Dissolved nickel phosphite; the buffer can be acetic acid or propionic acid in addition to ammonium chloride. the

The stabilizer used is mainly used to inhibit the catalytic activity of some active particles in the plating solution, so that the reduction reaction of nickel ions is only carried out on the surface of the substrate to be plated, so as to prevent the spontaneous decomposition of the plating solution, stabilize the plating solution, and obtain a high-quality coating. The stabilizer is thiourea or thiosulfate, and the amount added is 5-10g/L. the

In the process of implementing electroless plating, sometimes an appropriate amount of accelerators, surfactants, rare earth elements, etc. are added to increase the deposition rate and improve the quality of the coating. Commonly used accelerators include propionic acid, succinic acid, glycine, sodium fluoride, etc., and commonly used surfactants include sodium lauryl sulfate, sodium dodecyl sulfate, etc. the

C. The post-plating heat treatment refers to that the post-plating workpiece is subjected to heat preservation treatment at a temperature of 180° C. for 6 hours in a drying oven. the

Coating adhesion test results

It can be seen from Figures 8 to 11 that some small peaks appeared in the coating after heat treatment, but these peaks do not represent the cracking of the coating, which is only the result of the roughness of the substrate surface. The real peak of coating cracking is relatively continuous and relatively high AE signal. the

It can also be seen from the table and the figure that the bonding force value of the coating after heat treatment has increased. the

Claims (1)

1. the technology that aluminum alloy part is carried out the processing of oil-free self lubrication coating comprises the preceding workpiece pre-treatment of plating, copper facing intermediate treatment, the processing of self-lubricating abrasion-resistant coating and plating post-heat-treated, it is characterized in that:

Workpiece pre-treatment before A, the described plating is that workpiece is carried out oil removal treatment, wherein Na in the degreasing fluid that is made into by tsp, yellow soda ash, water glass and water ₃PO ₄: 30g/L; Yellow soda ash Na ₂CO ₃: 25g/L; Water glass Na ₂SiO ₃: 8g/L, treatment temp: 70～75 ℃, the time: 2～5min;

B, described copper facing intermediate treatment are with the H of the workpiece of handling through the A operation at 0.9～1.0mol/L ₂SO ₄, 0.75～0.85mol/L CuSO ₄5H ₂Carry out copper plating treatment in the copper-bath of O preparation, processing condition are: 20～25 ℃ of oxidizing temperatures, current density 1.0～2.5A/dm ², oxidization time 30min makes electrode with fine copper;

C, described self-lubricating abrasion-resistant coating are handled; Be in comprising the chemically composited liquid that nickel salt, reductive agent, complexing agent, buffer reagent, stablizer, antifriction phase material, accelerator and tensio-active agent are formed, to carry out the appositional pattern coating processing through the workpiece of B operation processing; Wherein nickel salt is controlled at 40～50g/L, and reductive agent is an inferior sodium phosphate, is controlled at 9～11g/L; Complexing agent is a trisodium citrate, is controlled at 90～110g/L; Buffer reagent is an ammonium chloride, is controlled at 40～60g/L; The antifriction phase material is MoS ₂, be controlled at 1.5～3g/L; Stablizer is thiocarbamide or thiosulphate, and the amount of adding is 5～10g/L; Described accelerator is propionic acid, Succinic Acid, Padil or Sodium Fluoride; Described tensio-active agent is cetyl trimethylammonium bromide or Tween-60, and the manipulated variable of adding respectively is 6-7mg/L or 0.40-0.5g/L; Solution temperature when depositing coating is controlled at 90～95 ℃, and the solution pH value is controlled at 8.5～10;

D, described plating post-heat-treated are meant plating back workpiece are handled at 6 hours heat preservation and drynesses that loft drier carries out under 180 ℃ of temperature.

Images