JP2009180408A - Protective member and protective device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective member capable of sufficiently protecting against a penetrating performance of a flying object such as a bullet or a bullet, which is drastically improved.
A base part is formed by forming a receiving part 2 from ceramics and a base 3 located on the back side of the receiving part 2 as a protective member 1 made of a material having a lower thermal expansion coefficient than the receiving part 2. 3 is maintained in a state where a compressive force is applied, so that the performance of blocking the bullets and bullets that have landed is improved. Moreover, since the progress of the crack generated on the impact receiving surface 2a is stopped at the boundary with the base 3, the characteristics of the two materials are sufficiently exhibited, and the protective performance can be enhanced by a synergistic effect.
[Selection] Figure 1

Description

  The present invention relates to a protective member that is lightweight and has high mechanical properties, and a protective device using the protective member. In particular, protective members for protecting the human body, vehicles, ships, aircraft, etc. by limiting the penetration of flying objects such as bullets and ammunition and sharp blades, and bulletproof vests, blade-proof vests, blade-proof shields, and bulletproofs using the same. The present invention relates to protective devices such as functional bags, bulletproof helmets, and bulletproof plates.

  The currently used protective members are required to be light in weight and have a high compressive strength because a large compressive stress is applied by bullets and shells. Examples of materials that are lightweight and have high mechanical properties include boron carbide ceramics and silicon carbide ceramics, and these are actually used as materials for protective members against bullets and shells.

  As described above, in Patent Document 1, as a protective member having high compressive strength, an impact-resistant reinforcing body made mainly of ceramics is placed in a cover covering the outside of the helmet at positions corresponding to the front and back of the helmet. A bulletproof appendage for helmets has been proposed, and it is described that the main component of ceramic is composed of at least one selected from silicon carbide, boron carbide, silicon nitride and alumina.

Patent Document 2 proposes a ceramic style which is a polygonal ceramic tile, and the thickness of the apex portion of the tile is thicker than the thickness of the center portion of the tile. It is described that this ceramic style is alumina, silicon nitride, silicon carbide, zirconia, or boron carbide, and is for a bulletproof plate, a bulletproof vest, or a blade-proof vest.
JP 2002-294512 A JP 2002-326861 A

  However, at the present time when penetrating performance of bullets and shells has been drastically improved, there is a demand for a light-weight protective member that is further superior in protective performance.

  An object of the present invention is to provide a lightweight protective member having improved protection performance against bullets and shells with high penetration performance, and a protective device using the same.

  In order to solve the above-described problems, the protection member of the present invention is configured such that the receiving portion is made of ceramics, and the base located on the back side of the receiving portion is made of a material having a lower thermal expansion coefficient than the receiving portion. It is characterized by that. In addition, a reinforcing part that reinforces the base part may be disposed on the back side of the base part, and the reinforcing part may be made of a material having a higher thermal expansion coefficient than the base part. Moreover, the material which comprises the said reinforcement part is good in it being the same material as the ceramics which comprise the said receiving part. Further, the ceramic constituting the impact receiving portion may be composed of boron carbide as a main component, the base portion as a ceramic, and the ceramic as a main component. Moreover, it is good to contain graphite and silicon carbide in the ceramics which comprise the said receiving part. Further, the ceramic constituting the impact receiving portion may be composed of silicon carbide as a main component, the base portion as a ceramic, and the ceramic as a main component. Moreover, it is good to make a receiving surface into a convex curved surface.

  The protective device of the present invention is characterized in that a plurality of the protective members are provided on a base.

  According to the protective member of the present invention, the impact receiving portion is made of ceramics, and the base portion located on the back side of the impact receiving portion is made of a material having a lower thermal expansion coefficient than the impact receiving portion. Since the state in which the compressive force is applied from the direction perpendicular to the direction in which the bullets and shells land is maintained, the performance of preventing penetration of bullets and shells is improved.

  Further, according to the protective member of the present invention, when a reinforcing portion for reinforcing the base portion is disposed on the back side of the base portion, and the reinforcing portion is made of a material having a higher thermal expansion coefficient than the base portion, Since the state in which a higher compressive force is applied from the direction perpendicular to the direction in which the bullets and shells land is maintained, the performance of preventing the penetration of bullets and shells is further improved.

  Further, according to the protective member of the present invention, when the material constituting the reinforcing portion is the same material as the ceramic constituting the impact receiving portion, an equivalent compressive force is applied to the base on both sides in the thickness direction of the base. Therefore, the ability to prevent penetration of bullets and shells is further improved.

  Further, according to the protective member of the present invention, the ceramic constituting the impact receiving portion is composed of boron carbide as a main component and the base is composed of ceramic, and the ceramic is composed of silicon carbide as the main component. Since both have low specific gravity, they are particularly suitable for use in bulletproof vests and bulletproof helmets for protecting the human body. Further, since the difference between the thermal expansion coefficient of ceramics mainly composed of boron carbide and the thermal expansion coefficient of ceramics mainly composed of silicon carbide is small, it is preferable that cracks hardly occur after the firing step.

  Further, according to the protective member of the present invention, the ceramic constituting the impact receiving portion is mainly composed of boron carbide, and when graphite and silicon carbide are contained in the ceramic, the graphite is composed of boron carbide particles. Suppressing abnormal grain growth and progressing densification of ceramics, silicon carbide strongly binds boron carbide particles by evaporation and condensation mechanisms in the firing process, so the compressive strength that is a required characteristic of protective members is increased. Can be higher.

  Further, according to the protective member of the present invention, when the ceramic constituting the impact receiving portion is composed of silicon carbide as a main component and the base is composed of ceramic, the ceramic is composed of silicon nitride as the main component. Since the difference between the thermal expansion coefficient of ceramics mainly composed of silicon carbide and the thermal expansion coefficient of ceramics mainly composed of nitriding coefficient is small, it is preferable that cracks hardly occur after the firing step. In addition, since the main component of the ceramic constituting the base portion is silicon nitride, the base portion has high fracture toughness, and even if a bullet or a bullet hits, cracks hardly progress.

  Furthermore, according to the protection member of the present invention, since the impact surface is a convex curved surface, it is possible to greatly reduce the probability that the flight direction of bullets and shells and the normal of the impact surface coincide. As a result, bullets and shells are landed so as to slide on the impact surface, so that the destructive energy is absorbed or dissipated and the protection performance can be further improved.

  Since the protective device of the present invention uses a plurality of protective members with high protective performance as described above, penetration of bullets and shells can be reduced with high probability.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings schematically shown.

  FIG. 1 is a perspective view schematically showing one embodiment of the protection member of the present invention, and FIGS. 2 to 3 are perspective views showing other embodiments of the protection member of the present invention. In addition, the same code | symbol is used when showing a common site | part in drawing.

  A protective member 1 shown in FIG. 1 is made of a ceramic receiving portion 2 having a receiving surface 2a for receiving impacts from flying objects such as bullets and shells, blades, and other external impacts. The base 3 positioned on the back surface 2b side of the base 2 is made of a material having a lower thermal expansion coefficient than the impact receiving portion 2, and the impact receiving portion 2 and the base 3 are directly joined by, for example, sintering. By adopting such a configuration, the base 3 is maintained in a state in which a compressive force is applied in a direction perpendicular to the direction in which the bullets and shells are landed. improves.

  The protective member 1 shown in FIG. 2 has substantially the same structure as the protective member 1 shown in FIG. 1, but the surface (back surface) 2 b where the receiving part 2 faces the base part 3 and the base part 3 faces the receiving part 2. The difference is that the surface 3 a to be bonded is joined via the bonding layer 4. Since the bonding layer 4 is thin, the compressive force applied to the base 3 is hardly lost. For example, the thickness is 1 μm or more and 4 μm or less, and cyanoacrylate resin, epoxy resin, phenol resin, polyurethane resin, acrylic resin, etc. It is preferable to form it from at least one of resin, vinyl acetate resin, vinyl chloride resin and urea resin.

  The protection member 1 shown in FIG. 3 has substantially the same configuration as the protection member 1 shown in FIG. 1, except that the impact receiving surface 2a is a convex curved surface. Such a convex curved surface can greatly reduce the probability that the direction in which the bullets and shells fly and the normal line of the impact receiving surface 2a coincide. As a result, bullets and shells land while sliding on the impact receiving surface 2a, so that the destruction energy is absorbed or dissipated, and the protection performance can be further enhanced.

  In particular, the protective member 1 shown in FIGS. 1 to 3 has a specific gravity when the main component of the ceramic constituting the impact receiving portion 2 is boron carbide and the main component of the ceramic constituting the base portion 3 is silicon carbide. Therefore, when it is used for a bulletproof vest, a bulletproof helmet, etc. for protecting a human body, it is light and suitable.

  In addition, since the impact receiving portion 2 is required to have a capability of restricting the penetration of bullets and shells, it is preferable that the impact receiving portion 2 has higher hardness and rigidity. From this point of view, it is desirable that the content of boron carbide is as high as possible, and this content is preferably 90% by mass or more, and more preferably 98% by mass or more with respect to 100% by mass of the ceramic constituting the impact receiving portion 2. .

  In the present embodiment, a component occupying 70% by mass or more among components constituting the material of interest is referred to as a main component. Further, in order to increase the hardness, rigidity and compressive strength, it is important to densify the ceramics constituting the impact receiving portion 2, and the relative density is desirably 95% by mass or more, and more desirably 99% by mass or more.

The Vickers hardness, Young's modulus, fracture toughness and compressive strength of the ceramics mainly composed of boron carbide are 22 GPa to 38 GPa, 330 GPa to 500 GPa, 2 MPa · m ^{1/2 to} 5 MPa · m ^1/2 , respectively. .5 GPa or more and 5 GPa or less, and these mechanical properties are respectively an indenter press-in (IF) method or a SEPB method, JIS R 1608-2003 defined by JIS R 1610-2003, JIS R 1602-1995, JIS R 1607-1995. Can be determined in accordance with.

  However, when the thickness of the ceramic is thin and the test piece defined by the JIS standard cannot be cut out from the impact receiving portion 2, the thickness of the impact receiving portion 2 may be the thickness of the test piece.

  In addition, the difference between the thermal expansion coefficient of ceramics containing boron carbide as the main component (hereinafter referred to as boron carbide ceramics) and the thermal expansion coefficient of ceramics containing silicon carbide as the main component (hereinafter referred to as silicon carbide ceramics) is small. Therefore, it is preferable that cracks do not easily occur after the firing step.

For example, the thermal expansion coefficients at 40 to 400 ° C. of boron carbide ceramics and silicon carbide ceramics are 4.5 × 10 ⁻⁶ / ° C. or more and 6 × 10 ⁻⁶ / ° C. or less, 3 × 10 ⁻⁶ / ° C. or more and 4 ×, respectively. 10 ⁻⁶ / ° C. or less, and these thermal expansion coefficients can be determined according to JIS R 1618-2002.

  Further, according to the protective member 1 of the present embodiment, the ceramic constituting the impact receiving portion 2 is mainly composed of boron carbide, and graphite and silicon carbide are contained in the ceramic mainly composed of boron carbide. In some cases, the compressive strength, which is a required characteristic of the protective member, can be further increased, which is more preferable.

  Graphite and silicon carbide act as sintering aids in the firing process of boron carbide ceramics, graphite suppresses abnormal grain growth of boron carbide particles and promotes densification of boron carbide ceramics, and silicon carbide fires Since the boron carbide particles are firmly bonded by the evaporation and condensation mechanism in the process, the compressive strength of the boron carbide ceramic can be increased. In particular, the silicon carbide powder is preferably an α-type silicon carbide powder, and by using the α-type silicon carbide powder, the α-type silicon carbide grows into a plate shape during firing, and the α-type silicon carbide crystal. Become particles. Even if the boron carbide ceramic has a minute crack, the crack is difficult to progress due to the presence of the α-type silicon carbide crystal particles grown in a plate shape.

  FIG. 4 schematically shows the crystal structure of carbon, (a) is a schematic diagram showing the crystal structure of graphitizable carbon, and (b) is a schematic diagram showing the crystal structure of non-graphitizable carbon. . The crystal structure of graphite affects the pores in the crystal grains of the graphite, and when the crystal structure of the graphite is a structure in which the carbon layer surface has an orderly orientation as shown in FIG. Since the pores in the crystal particles are reduced, the compressive strength can be increased. As shown in FIG. 4B, when the graphite crystal structure is a disordered three-dimensional network structure twisted so that ribbon-like stacks with long carbon layers are entangled, pores in the graphite crystal particles increase. Therefore, the compressive strength is reduced.

  In the boron carbide ceramics forming the protective member of the present embodiment, it is preferable that the half width from the (002) plane of graphite is 0.3 ° or less (excluding 0 °) as measured by the X-ray diffraction method. It is. Further, the crystal structure of graphite is the structure shown in FIG. 4A, and further, mechanical properties such as compressive strength, such as bending strength, Young's modulus, hardness, etc., can be increased.

  FIG. 5 is an example of an X-ray diffraction chart of boron carbide ceramics forming the protective member of the present embodiment. As shown in FIG. 5, the peak from the (002) plane is represented as a peak (p). Here, the half width from the (002) plane refers to the width of the diffraction angle (2θ) at the half value of the peak (p). By setting this width to 0.3 ° or less (excluding 0 °), the crystal structure of graphite becomes the structure shown in FIG. 4 (a). As a result of the reduction of pores in the graphite crystal particles, the compression strength is increased. can do. In particular, the crystal structure of graphite is a hexagonal system called 2H graphite, and is preferably a crystal structure shown by JCPDS card # 41-1487.

  Further, it is preferable that graphite is contained in an amount of 1 to 10% by mass with respect to 100% by mass of boron carbide ceramics, and silicon carbide is contained in an amount of 0.5 to 5% by mass with respect to 100% by mass of boron carbide ceramics. . As a result, boron (B) and carbon (C) atoms are easily moved during firing, and as a result of sufficient densification, the compressive strength, which is one of the required characteristics of the protective member, can be increased.

  The graphite and silicon carbide in the boron carbide ceramic can be identified by, for example, an X-ray diffraction method using CuKα rays. In addition, quantitative analysis of graphite can be performed using X-ray diffraction using the Rietveld method.

Specifically, first, a calibration curve is created in advance. That is, a mixed powder of graphite powder and boron carbide powder is prepared. For mixed powders with different composition ratios, the area I (C) of the X-ray diffraction peak attributed to the (002) plane of graphite and the X-ray diffraction peak attributed to the (021) plane of boron carbide (B ₄ C) After obtaining the ratio I (C) / I (B ₄ C) of the area I (B ₄ C) and plotting it on a graph, a calibration curve consisting of a straight line is created using the least square method. FIG. 6 is an example of a calibration curve obtained from a mixed powder of graphite powder and boron carbide powder.

Next, using this calibration curve, the graphite content in the boron carbide ceramics is determined. That is, the ratio I (C) / I (B ₄ C) obtained by irradiating boron carbide ceramics with X-rays can be obtained, and the content of graphite in the boron carbide ceramics can be measured from the calibration curve.

  Furthermore, the quantitative analysis of silicon carbide can be measured using an ICP (Inductively Coupled Plasma) emission analysis method. Specifically, the content of Si can be measured by ICP emission analysis, and all of Si can be regarded as SiC, and converted to SiC, and the converted amount can be used as the content of silicon carbide. .

  In the protective member 1 shown in FIGS. 1 to 3, the ceramic constituting the impact receiving portion 2 is silicon carbide ceramics, and the main component of the ceramic constituting the base portion 3 is silicon nitride (hereinafter referred to as silicon nitride ceramics). In this case, the difference between the thermal expansion coefficient of the silicon carbide ceramics and the thermal expansion coefficient of the silicon nitride ceramics is small. Further, since the main component of the ceramic constituting the base portion 3 is silicon nitride, the base portion 3 has high fracture toughness, and even if a bullet or a bullet hits, cracks do not easily progress.

For example, the thermal expansion coefficients at 40 to 400 ° C. of silicon carbide ceramics and silicon nitride ceramics are 3 × 10 ⁻⁶ / ° C. or higher and 4 × 10 ⁻⁶ / ° C. or lower, 2 × 10 ⁻⁶ / ° C. or higher and 3 × 10 ^{− The} coefficient of thermal expansion can be determined in accordance with JIS R 1618-2002.

  Further, the fracture toughness of silicon nitride ceramics can be determined according to the indenter press-fit (IF) method or SEPB method defined in JIS R 1607-1995.

Further, when the base 3 is made of silicon nitride ceramics, from the viewpoint that the fracture toughness and strength can be increased, the composition formula Si _6-Z Al _Z O _Z N _8-Z (z = 0.1-1). Β-sialon represented as a main phase, and Al, Si, RE (RE is a periodic table group 3 element) component ratio is Al ₂ O ₃ , SiO ₂ , RE ₂ O ₃ conversion Al ₂ O _{3 respectively.} 5 to 50 mass%, SiO ₂ is 5 to 20 mass%, the grain boundary phase and the balance is predominantly _{RE 2 O 3 RE-Al-} SiO-N, consisting of a main phase and a grain boundary phase ceramics It is preferable to form a silicon nitride ceramic containing 4 to 20% by volume of Fe and containing Fe silicide particles in an amount of 0.02 to 3% by mass with respect to the ceramic in terms of Fe.

  Here, the solid solution amount z can be calculated as follows. That is, silicon nitride ceramics was pulverized to a particle size of 200 mesh or less, and the obtained powder was used as a sample for correcting the angle of diffraction in the powder X-ray diffraction method as a high purity α-silicon nitride powder (E-10 grade manufactured by Ube Industries). , Al content is 20 ppm or less), and uniformly mixed in a mortar. By powder X-ray diffraction method, the analysis range 2θ is 33 to 37 °, the scanning step width is 0.002 °, Cu— The profile intensity is measured with the Kα line (λ = 1.54056Å). The angle is corrected using the maximum peak value obtained from the angle correction sample.

That is, the difference (Δ2θ ₁ ) between the average 2θ of the upper 10 points of peak intensity obtained every 0.002 ° of α (102) that appears in the vicinity of 2θ = 34.565 ° (Δ2θ ₁ ), and 2θ = 35 The difference (Δ2θ ₂ ) between the average 2θ of the top 10 peak intensities obtained every 0.002 ° of α (210) appearing near .333 ° and 35.333 ° (Δ2θ ₂ ) is obtained, respectively, and the average of the differences (Δ2θ Let ₁ + Δ2θ ₂ ) / 2 be the correction Δ2θ. Next, the angle obtained by correcting the average 2θ of the top 10 peak intensities obtained every 0.002 ° of β (210) appearing in the vicinity of 2θ = 36.055 ° by the correction Δ2θ is the peak position of β (210) ( 2θ _β ). Then, the lattice constant a (Å) is calculated by substituting the peak position (2θ _β ), λ = 1.54056Å, (hkl) = (210) into the following equation.

sin ² θ _β = λ ² (h ² + hk + k ² ) / (3a ² ) + λ ² l ² / (4c ² )
In this equation, the calculated lattice constant a (Å) and the lattice constant a (Å) −solid solution amount z described in KH Jack, J. Mater. Sci., 11 (1976) 1135-1158, FIG. From this graph, the solid solution amount z can be determined.

The grain boundary phase consists RE-Al-SiO-N, Al, Si, the component ratio of RE is _{Al 2 O 3, SiO 2,} RE 2 O 3 in terms of in _Al 2 _{O 3} is from 5 to 50 mass %, SiO ₂ is 5 to 20% by mass, and the balance is mainly RE ₂ O ₃ , and it is preferable that the content is 4 to 20% by volume with respect to the ceramic composed of the main phase and the grain boundary phase. In the present embodiment, the composition ratio of the grain boundary phase is expressed with the sum of Al ₂ O ₃ , SiO ₂ , RE ₂ O ₃ and N being 100 mass%.

Here, in general, an oxide containing RE-Al-Si-O promotes densification of silicon nitride and sialon. Powder materials such as Al ₂ O ₃ , SiO ₂ , and RE ₂ O ₃ react as the temperature rises to generate a liquid phase that is well wetted with silicon nitride and sialon at 1400 ° C. or higher, and then dissolve silicon nitride and sialon. By doing so, a grain boundary phase composed of RE-Al-Si-O-N is formed.

  The volume ratio of the grain boundary phase to the ceramic affects the strength of the silicon nitride ceramic, and the ratio is preferably 4 to 20% by volume.

Such a composition ratio of Al ₂ O ₃ , SiO ₂ , RE ₂ O ₃ and a volume ratio of the grain boundary phase can be obtained as follows. First, each ratio (mass%) of RE and Al in ceramics is measured by ICP (Inductivity Coupled Plasma) spectroscopy, and this ratio (mass%) is set to RE ₂ O ₃ and Al ₂ O ₃ , respectively. Convert to ratio (mass%). Next, the ratio of all oxygen in the ceramics is measured by an oxygen analyzer using an oxygen analyzer (manufactured by LECO, model TC-136), and the ratio of oxygen in RE ₂ O ₃ and Al ₂ O ₃ is subtracted. The ratio of the remaining oxygen is converted into the ratio (mass%) of SiO ₂ . The balance in the ceramic is regarded as Si ₃ N _4, and the respective ratios (mass%) are set to the respective theoretical densities (Y ₂ O ₃ : 5.02 g / cm ³ , Er ₂ O ₃ : 8.64 g / cm ³ , Yb _2). O ₃ : 9.18 g / cm ³ , Lu ₂ O ₃ : 9.42 g / cm ³ , Al ₂ O ₃ : 3.98 g / cm ³ , SiO ₂ : 2.655 g / cm ³ , Si ₃ N ₄ : 3 .18 g / cm ³ ) to calculate the volume ratio of the grain boundary phase.

Next, the ratio (mass%) of nitrogen (N) contained in the grain boundary phase is calculated using energy dispersive X-ray spectroscopy (EDS), and Al ₂ O ₃ , SiO ₂ , RE ₂ O ₃ and The composition ratio of the grain boundary phase is calculated with the sum of the ratios (mass%) of nitrogen (N) as 100%. However, since the composition ratio of nitrogen contained in the grain boundary phase of the silicon nitride ceramic used in the present embodiment is a very small amount and is usually 0.1% by mass or less, it will be described as being included in RE ₂ O ₃ hereinafter. .

  The RE in the grain boundary phase may be a Group 3 element of the periodic table, such as Er, Yb, Lu, etc., but RE is preferably Y. This is because Y is a light element among the Group 3 elements of the periodic table and can be reduced in weight. Moreover, what is necessary is just to measure 4-point bending strength based on JISR1604-1995.

  Further, since the Fe silicide particles in the silicon nitride ceramics affect the fracture toughness and strength of the ceramics, the Fe silicide particles contain 0.02 to 3 mass% with respect to the ceramics in terms of Fe. Is preferred.

  Fe silicide has a large coefficient of thermal expansion and is thought to generate residual stress on β-sialon particles and grain boundary phase, and is one of the effects and forms of fracture to improve the fracture toughness of ceramics. When grain boundary sliding occurs, it acts like a wedge that prevents the sliding of β-sialon particles, and has the effect of improving strength. The Fe silicide acts as one of the liquid phase components during firing, and is effective in improving the sinterability. The form of such Fe silicide can be confirmed by elemental analysis using a powder X-ray diffraction method or X-ray microanalyzer (EPMA), and can be quantified by ICP spectroscopy.

The Fe silicide is interspersed as particles having a particle size of 50 μm or less, preferably 2 to 30 μm in the grain boundary phase composed of β-sialon particles or RE-Al—Si—O—N. _{and, FeSi 2, FeSi, Fe 3} Si, is preferably present in the form of _Fe 5 Si _3, it is preferable that particularly FeSi ₂ (JCPDS # 35-0822).

  Since such a protective member 1 is required to be lightweight, it is preferable that the receiving part 2 and the base part 3 have a flat plate shape. For example, both the receiving part 2 and the base part 3 have a length of 10 mm or more and 400 mm. Hereinafter, a flat plate having a width of 10 mm to 400 mm and a thickness of 1 mm to 20 mm.

  FIG. 7 is a perspective view showing another embodiment of the protective member of the present invention.

  In the protective member 1 shown in FIG. 7, a reinforcing portion 5 that reinforces the base portion 3 is disposed on the back side of the base portion 3, and the reinforcing portion 5 is made of a material having a higher thermal expansion coefficient than the base portion 3. With such a configuration, the base 3 is maintained in a state in which a higher compression force is applied from a direction perpendicular to the direction in which the bullets and shells are landed. Further improve.

  In particular, when the material constituting the reinforcing portion 5 is the same material as the ceramic constituting the impact receiving portion 2, since the same compressive force is applied to the base portion on both sides in the thickness direction of the base portion 3, the mechanical characteristics are deteriorated. This is preferable.

  In the present embodiment, the same material does not need to be the same components up to the sintering aid and unavoidable impurities, and means that the main components are the same components.

  Since the protective member 1 shown in FIG. 7 is also required to be lighter, it is preferable that the receiving part 2 and the base part 3 have a flat plate shape. For example, the receiving part 2, the base part 3 and the reinforcing part 5 include: Each flat plate has a length of 10 mm to 400 mm, a width of 10 mm to 400 mm, and a thickness of 1 mm to 20 mm.

  The above-mentioned protective members are classified into two types according to their performance, and include reactive protective members that contain explosive substances inside and that explode substances strike against the explosives when a projectile such as a bullet or a bullet hits, and bullets. There are passive protective members that prevent penetration of flying objects such as shells and shells, and it is particularly preferable to use them as passive protective members.

  In the protective member of the present embodiment, it is preferable that the base portion 3 or the reinforcing portion 5 is in contact with at least one of fiber reinforced plastic (FRP) including polyethylene fiber, aramid fiber, and carbon fiber on the back surface. is there. Polyethylene fiber, aramid fiber and carbon fiber have high knot strength, so they can absorb or dissipate the destructive energy of bullets and shells, and can reduce secondary damage caused by ceramic debris scattered upon landing. It is.

  Since the protective member according to the present embodiment has high protective performance as described above, a plurality of protective members are fixed on a suitable base, and a bulletproof vest, a blade-proof vest, a blade-proof shield, a bag with a bulletproof function, It is also suitable for use in a protective device such as a helmet and a protective device such as a bulletproof plate.

  Here, as an example of the protective member of the present embodiment, a manufacturing method in the case where the ceramics constituting the impact receiving part 3 is boron carbide ceramics and the ceramics constituting the base part 5 is silicon carbide ceramics will be described.

First, a boron carbide powder having an average particle size (D ₅₀ ) of 0.5 to 2 μm is prepared. The boron carbide powder to be prepared is composed of powder having a molar ratio of boron (B) to carbon (C) (B / C ratio) having a stoichiometric ratio of 4, ie, boron carbide (B ₄ C). In addition to the powder, the molar ratio (B / C ratio) is 3.5 or more and less than 4, or the molar ratio (B / C ratio) is larger than 4 and 10 or less, such as B ₁₃ C ₂ A mixed powder or a powder mixed with carbon, boric acid, boric anhydride, iron, aluminum, silicon, or the like may be used.

  When these powders are used, by adding graphite powder and silicon carbide powder as sintering aids to these powders, sintering can be performed without applying mechanical pressure during firing. The boron carbide powder is desirably a fine powder having an average particle diameter of 0.5 to 2 μm, but a powder having a large average particle diameter of about 20 μm, for example, or boron carbide powder obtained by pre-grinding this powder is also used. Is possible. Here, the preliminary pulverization is preferably performed by a jet mill or the like that does not use a pulverizing medium in order to reduce contamination with impurities.

  In order to contain graphite in an amount of 1% by mass to 10% by mass with respect to boron carbide ceramics and silicon carbide in an amount of 0.5% by mass to 5% by mass with respect to boron carbide ceramics, the graphite powder is used as described above. What is necessary is just to make 1 mass% or more and 10 mass% or less of silicon carbide powder with respect to the powder total, and 0.5 mass% or more and 5 mass% or less with respect to the said powder total.

  In order for the graphite contained in boron carbide ceramics to have a half-value width of 0.3 ° or less (excluding 0 °) from the (002) plane measured by the X-ray diffraction method, the (002) plane Graphite powder having a half-width from 0.34 ° or less (excluding 0 °) may be used. When the half width of the graphite powder is wide, the crystallinity of the graphite powder is low, and when the half width is narrow, the crystallinity of the graphite powder is high. In order to obtain graphite powder with high crystallinity, it is only necessary to limit the distance that carbon atoms can move in the step of graphitizing from carbon. Specifically, the orientation of carbon may be controlled during this step. As such graphite powder, for example, highly oriented pyrolytic graphite (HOPG) powder may be used.

  As the sintering aid, in addition to graphite powder and silicon carbide powder, at least one of zirconium boride, titanium boride, chromium boride, zirconium oxide and yttrium oxide may be added to promote sintering. .

  Second, the prepared boron carbide powder and sintering aid are put into a mill such as a rotary mill, a vibration mill, a bead mill, etc., and wet-mixed with at least one of water, acetone, and isopropanol (IPA). Is made. As the grinding media, media coated with an imide resin on the surface or media made of various ceramics such as boron nitride, silicon carbide, silicon nitride, zirconium oxide, or aluminum oxide can be used. A medium made of boron nitride ceramic as a material or a medium whose surface is coated with an imide resin is preferable. Moreover, you may add a dispersing agent before a grinding | pulverization in order to reduce the viscosity of the obtained slurry.

  Third, the obtained slurry is dried to produce granules containing boron carbide as a main component (hereinafter referred to as boron carbide granules). Prior to this drying, the slurry is passed through a mesh smaller than 200 mesh to remove coarse impurities and debris, and iron and its compounds are removed by removing iron with a magnetic iron remover. It is preferable to do. In addition, a binder such as paraffin wax, polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyethylene oxide (PEO), acrylic resin is added to the slurry in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the powder in the slurry. It is preferable to mix, since it is possible to suppress the occurrence of cracks and cracks in the molded body in the molding step described later. As a method for drying the slurry, the slurry may be heated in a container and dried, or may be dried by a spray drying method using a spray dryer or the like, or may be dried by other methods. .

  Fourth, water, a dispersing agent, boron carbide powder, and a sintering aid such as phenol resin are added to silicon carbide powder, mixed and pulverized with a ball mill to form a slurry, and a binder is added to and mixed with this slurry, followed by spraying. Granules mainly composed of silicon carbide (hereinafter referred to as silicon carbide granules) are prepared by drying.

  The boron content with respect to silicon carbide ceramics is affected by the boron carbide powder to be added, so that the boron content is 0.1% by mass or more and 0.5% by mass or less with respect to 100% by mass of silicon carbide ceramics. The boron carbide powder content may be 0.12 mass% or more and 0.64 mass% or less with respect to the silicon carbide powder.

  Fifth, silicon carbide granules and boron carbide granules are sequentially filled into a mold, and a relative density of 45 to 70% is obtained using a known molding method such as a dry pressure molding method or an isotropic pressure molding method. A desired shape is obtained. In order to produce a protective member having a structure that can more sufficiently restrict the penetration of flying objects such as bullets and shells, it is preferable that the surface that becomes the impact surface after firing is a convex curved surface.

  Sixth, the binder is degreased at a temperature of 500 to 900 ° C. in a nitrogen atmosphere or a vacuum atmosphere.

  Seventh, a firing furnace heated by a resistance heating element made of graphite is used as a firing furnace, and a degreased body is disposed in the firing furnace. Preferably, they are placed in a firing container that can enclose the entire degreased body (hereinafter referred to as a firing jig). This is because foreign matter that may adhere to the degreased body from the atmosphere in the firing furnace (for example, carbon pieces scattered from a graphite heating element or a carbon heat insulating material, or other inorganic materials incorporated in the firing furnace) This is for the purpose of reducing the adhesion of small pieces of the heat insulating material made, and for reducing the scattering of volatile components from the molded body. The material for the firing jig is desirably graphite, and may be a material such as silicon carbide or a composite thereof. Furthermore, it is preferable to surround the entire degreased body with the firing jig.

  Eighth, the degreased body placed on the firing jig is placed in a firing furnace and held in a temperature range of 1800 ° C. or higher and lower than 2000 ° C. for 10 minutes to 10 hours in argon gas, helium gas or vacuum. (After the first step), the mixture is held at a temperature of 2000 ° C. or higher and 2350 ° C. or lower for 10 minutes to 20 hours (second step) to be densified to a relative density of 90% or higher. The heating rate is preferably 1 to 30 ° C./min. Here, the holding in the first and second steps means the total time spent in a predetermined temperature range. For example, the holding time, the temperature rising time, and the temperature falling time are holding times. include. In addition, since it decomposes | disassembles a boron carbide and an additive component when it hold | maintains at 2000 degreeC or more, it is desirable to hold | maintain in argon gas or helium gas.

  In order to further promote densification, pressurization may be performed with a higher pressure gas when the open porosity becomes 5% or less. As this pressurizing method, it is preferable to use a method of pressurizing at a gas pressure of 1 to 300 MPa by a high pressure GPS (Gas Pressure Sintering) method or a hot isostatic press (HIP) method, and relative to this. In particular, the density can be increased to 95% or more. Moreover, you may sinter by the method of applying a mechanical pressure like the hot press method and SPS (Spark Plasma Sintering) method as needed.

  According to the manufacturing method described above, it is possible to obtain the protective member of the present embodiment in which the ceramic constituting the impact receiving portion 2 is boron carbide ceramics and the ceramic constituting the base portion 3 is silicon carbide ceramics.

  When the reinforcing portion 5 is disposed on the back side of the base portion 3 and the reinforcing portion 5 is made of boron carbide ceramics, the boron carbide granules, silicon carbide granules, and boron carbide obtained by spray drying described above. The granules are sequentially filled in a mold, and the above-described molding method, degreasing method, and firing method may be used.

  Next, as another example of the protective member, a manufacturing method in the case where the ceramic constituting the impact receiving portion 2 is silicon carbide ceramics and the ceramic constituting the base portion 3 is silicon nitride ceramic will be described.

  First, silicon carbide granules are prepared by the same method as described above.

  Second, silicon carbide granules are filled into a predetermined mold, and a desired shape having a relative density of 45 to 70% is obtained by using a known molding method such as a dry pressure molding method or an isotropic pressure molding method. To do. In order to produce a protective member having a structure that can more sufficiently restrict the penetration of flying objects such as bullets and shells, it is preferable that the surface that becomes the impact surface after firing is a convex curved surface.

  Third, the temperature is raised in a nitrogen atmosphere for 10 to 40 hours, held at 450 to 650 ° C. for 2 to 10 hours, and then naturally cooled and degreased.

  Fourth, for example, silicon carbide ceramics can be obtained by holding at a temperature of 1800 to 2200 ° C. for 1 to 10 hours in an inert gas atmosphere. Hot pressing may be performed at 50 MPa.

Fifth, in the case where the base 3 is made of silicon nitride ceramic, the β conversion rate of the silicon nitride-based powder is 40% or less, and the solid solution amount in the composition formula Si _6-Z Al _Z O _Z N _8-Z A silicon nitride powder having z of 0.5 or less and Al ₂ O ₃ , SiO ₂ , RE ₂ O ₃ , and Fe ₂ O ₃ powders as additive components, a barrel mill, a rotating mill, a vibration mill, and a bead mill Etc. are wet-mixed and pulverized into a slurry.

Here, the sum of the powders of Al ₂ O ₃ , SiO ₂ , and RE ₂ O ₃ as additive components is 100% by volume when the total of the silicon nitride powder and the powder of these additive components is 100% by volume. What is necessary is just to make it become 4-20 volume%.

  There are two types of silicon nitride, α-type and β-type, due to the difference in crystal structure of silicon nitride. The α type is stable at low temperatures, the β type is stable at high temperatures, and the phase transition from α type to β type occurs irreversibly at 1400 ° C. or higher.

Here, the β conversion is the sum of the peak intensities of the α (102) diffraction line and the α (210) diffraction line obtained by the X-ray diffraction method, I _α , β (101) diffraction line and β ( 210) A value calculated by the following equation, where I _β is the sum of the peak intensities with the diffraction line.

β conversion rate = {I _β / (I _α + I _β )} × 100 (%)
The β conversion rate of silicon nitride-based powder affects the strength and fracture toughness value of silicon nitride ceramics. The reason why the silicon nitride-based powder having a β conversion ratio of 40% or less is used is that both the strength and the fracture toughness value can be increased. Silicon nitride-based powder having a β conversion ratio exceeding 40% becomes the core of grain growth in the firing step, tends to be coarse and have a small aspect ratio, and both strength and fracture toughness values are reduced. In particular, it is preferable to use a silicon nitride-based powder having a β conversion rate of 10% or less, whereby the solid solution amount z can be made 0.1 or more.

  The media used for pulverizing the silicon nitride-based powder can be media made of various ceramics such as silicon nitride, zirconia, and alumina. However, media made of silicon nitride ceramics that are difficult to mix impurities or the same material composition are used. Is preferred.

Note that the silicon nitride powder is pulverized until the particle size (D ₉₀ ) at which the cumulative volume is 90% when the total cumulative volume of the particle size distribution curve is 100% is 3 μm or less. This is preferable from the viewpoints of improvement in cohesiveness and formation of needles in the crystal structure. The particle size distribution obtained by grinding can be adjusted by the outer diameter of the media, the amount of the media, the viscosity of the slurry, the grinding time, and the like. In order to reduce the viscosity of the slurry, it is preferable to add a dispersant, and in order to pulverize in a short time, it is preferable to use a powder having a particle size (D ₅₀ ) of 1 μm or less that has a cumulative volume of 50% in advance.

  Sixth, the obtained slurry is passed through a mesh finer than 200 mesh and then dried to obtain granules containing silicon nitride as a main component (hereinafter referred to as silicon nitride granules). Moreover, it is preferable for moldability to mix organic binders, such as paraffin wax, polyvinyl alcohol (PVA), and polyethyleneglycol (PEG), with respect to 100 mass% of powder at the stage of a slurry. The drying may be performed by a spray drying method using a spray dryer or the like, or may be another method.

  Seventh, after the silicon nitride granule is filled into the mold, the silicon carbide ceramic obtained by the above-described method is placed on the silicon nitride granule, and is heated to 1700 ° C. or higher and 1800 ° C. by hot pressing in a nitrogen atmosphere. The pressure is kept at 1 to 2 hours while applying a pressure of less than 20 to 40 MPa.

  According to the manufacturing method described above, it is possible to obtain a protective member in which the ceramic constituting the receiving part 2 is silicon carbide ceramics and the ceramic constituting the base part 3 is silicon nitride ceramics.

  Further, when the reinforcing portion 5 is disposed on the back side of the base portion 3 and the reinforcing portion 5 is made of silicon carbide ceramics, the above-described silicon carbide ceramics, silicon nitride granules and silicon carbide ceramics are sequentially filled in the mold. The above-described firing method may be used.

  Furthermore, the protective device of this embodiment arrange | positions the protective member 1 obtained by the above-mentioned method on the base | substrate (for example, fiber reinforced plastic (FRP) containing a polyethylene fiber, an aramid fiber, and a carbon fiber), for example, Obtained by fixing with a urethane-based adhesive, penetration of bullets and shells can be reduced with high probability.

It is a perspective view which shows one Embodiment of the protection member of this invention. It is a perspective view which shows other embodiment of the protection member of this invention. It is a perspective view which shows other embodiment of the protection member of this invention. FIG. 2 schematically shows a crystal structure of carbon, (a) is a schematic diagram showing a crystal structure of graphitizable carbon, and (b) is a schematic diagram showing a crystal structure of non-graphitizable carbon. It is an example of the X-ray-diffraction chart of the boron carbide ceramics which comprise a protective member. It is an example of a calibration curve obtained from a mixed powder of graphite powder and boron carbide powder. It is a perspective view which shows other embodiment of the protection member of this invention.

Explanation of symbols

1: Protective member 2: Receiving part 3: Base part 4: Bonding layer 5: Reinforcing part

Claims (8)

A protective member comprising a receiving part made of ceramics, and a base located on the back side of the receiving part made of a material having a lower coefficient of thermal expansion than the receiving part. The protective member according to claim 1, wherein a reinforcing portion that reinforces the base portion is disposed on the back side of the base portion, and the reinforcing portion is made of a material having a higher thermal expansion coefficient than the base portion. The protective member according to claim 2, wherein the material constituting the reinforcing portion is the same material as the ceramic constituting the receiving portion. 4. The ceramic according to claim 1, wherein the ceramic constituting the impact receiving portion is boron carbide as a main component and the base is constituted as ceramic, and the ceramic is silicon carbide as a main component. Protective member according to the above. The protective member according to claim 4, wherein graphite and silicon carbide are contained in ceramics constituting the impact receiving portion. 4. The ceramic according to any one of claims 1 to 3, wherein the ceramic constituting the receiving portion is composed of silicon carbide as a main component and the base is composed of ceramic, and the ceramic is composed mainly of silicon nitride. Protective member according to the above. The protection member according to claim 1, wherein the impact receiving surface is a convex curved surface. A protective device comprising a plurality of protective members according to any one of claims 1 to 7 on a base.

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