Plastic injection molding bonding method for ceramic matrix composite shell

Abstract

The invention relates to a plastic injection bonding method for a ceramic-based composite material shell, and belongs to the technical field of ceramic-based composite material preparation and connection. The plastic injection bonding method comprises the following steps: S1, selecting a ceramic shell with a preset positioning groove as a matrix; s2, selecting a plastic component with a nut column, wherein the size of the plastic component is smaller than that of the positioning groove so as to reserve a glue layer gap; s3, the interior of the positioning groove is coated with a double-component structure adhesive; s4, pressing the plastic component into the groove by using a centering jig, limiting and correcting the position of the nut column by using the jig, and performing tolerance compensation by using the uncured glue layer; and S5, maintaining the pressure and curing at the set temperature of 120 DEG C and the pressure of 0.8 MPa. According to the preparation method, a continuous and compact chemical bonding interface is constructed between the matrix and the new ceramic layer, so that the overall shear strength and the stripping resistance of the composite material are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite material preparation and bonding, specifically a plastic injection molding bonding method for ceramic matrix composite material shells. Background Technology

[0002] Currently, ship hull structures are mostly made of solid wood, cement, or marble. The internal assembly structures are usually fixed with nuts and glue to allow for the assembly and fixation of keyboard PCB components. However, this approach is prone to problems such as misalignment, skewness, and non-perpendicularity between the nuts. Its fatal flaw is that if the nuts are subjected to excessive force, it will be directly transmitted to the shell. If the torque of the nuts is weak, they will spin freely and slip, or exceed the shell's bearing limit, causing the shell to burst. Traditional ceramics are mainly used for crafts, collections, or medical products. There are no ceramic structural components on the market that can be used to assemble other components in complex electronic products. A single ceramic structure cannot meet the precision assembly requirements of electronic products, and the requirements for dimensional accuracy and deformation cannot be met.

[0003] The information disclosed in the background section above is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a plastic injection molding bonding method for ceramic matrix composite shells to solve the problems mentioned in the background art.

[0005] The technical solution of the present invention includes the following steps: S1. Pre-setting of ceramic substrate structure: Selecting a ceramic shell and pre-setting a positioning groove inside the ceramic shell for accommodating the plastic component, as a substrate that supports the appearance and structure; S2. Plastic component adaptation preparation: Select a plastic component, which integrates a nut post for subsequent assembly and locking, and the outline dimension of the plastic component is smaller than the size of the positioning groove, with a gap of 0.5mm-1.0mm reserved between them to accommodate the adhesive layer and for position adjustment; S3. Adaptation and application: Mix two-component structural adhesive at a mass ratio of 10:1 and apply it evenly to the positioning groove of the ceramic shell; S4. Precision fixture alignment and tolerance compensation: The plastic component is pressed into the positioning groove of the ceramic shell using a centering fixture. The physical limit of the fixture forces the center of the nut column of the plastic component to be aligned with the preset standard coordinates. At this time, the flow of structural adhesive is used to fill the gap caused by the sintering tolerance of the ceramic shell, so as to achieve independent positioning of the plastic component relative to the ceramic surface reference surface. S5. Pressure Holding and Curing: Place the assembled workpiece in a heating and pressure holding device and maintain it at a temperature of 120℃ and a pressure of 0.8MPa for 120 seconds until the adhesive is completely cured.

[0006] Optionally, it includes: a ceramic housing having a positioning groove on its inner surface; A plastic inner liner is embedded in the positioning groove, and one or more nut posts are provided on the plastic inner liner; A structural adhesive layer is used to fill the space between the ceramic outer shell and the plastic inner liner; The positional accuracy of the nut center position of the plastic inner liner relative to the surface reference surface of the ceramic outer shell is independent of the sintering tolerance of the ceramic outer shell and is compensated and corrected by the thickness of the cured structural adhesive layer.

[0007] Optionally, the ceramic shell is a ceramic hull structure that serves as a PCB inner liner for electronic products, and the outer surface of the ceramic hull has an ice crack or natural crazing texture structure formed by sintering.

[0008] Optionally, in step S3, the two-component structural adhesive is a high-temperature resistant epoxy resin AB adhesive, and its formulation ratio is 10:1 by mass of component A to component B. The adhesive is applied by an automated dispensing machine for trajectory coating.

[0009] Optionally, in step S4, the centering fixture is used in conjunction with a feeler gauge to control the gap. The feeler gauge has a thickness of 0.5mm-1.0mm to ensure that the plastic components are spaced evenly around the ceramic groove.

[0010] Optionally, in step S2, the physical roughening treatment uses 150-200 mesh silicon carbide or alumina sand for sandblasting, with a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation uses argon or argon-hydrogen mixed atmosphere, with a radio frequency power of 300-500 W and a processing time of 2-4 minutes.

[0011] Optionally, in step S5, the specific parameters of the pressure holding and curing process are as follows: the air pressure is set to 0.8 MPa, the heating temperature is constant at 120°C, and the pressure holding time is 120 s; the pressure is applied to the surface of the plastic component by a pneumatic clamp to ensure that the adhesive layer is dense and free of air bubbles.

[0012] Optionally, in step S4, the curing process is carried out in a constant temperature oven or hot press, and the curing environment must be kept clean and dust-free; the pressure fluctuation range of the pressure holding curing is controlled within ±0.05MPa.

[0013] Optionally, in step S4, the protective atmosphere is argon or nitrogen.

[0014] This invention provides an improved method for plastic injection molding bonding of a ceramic matrix composite shell, which has the following improvements and advantages compared with the prior art: 1. This invention is the first to combine high-strength ceramics with plastic parts for use in the outer shell and internal support structure of electronic products, achieving excellent structural compatibility and ensuring assembly strength; 2. By combining ceramics and plastics in a fixing process, the assembly accuracy is improved. The plastic mold ensures the accuracy of the nut column, allowing the remaining structural components of the product to be assembled normally into a finished product, effectively avoiding the problem of nut misalignment in traditional processes. 3. By using a specific glue ratio (10:1) and a high-temperature and high-pressure curing process (0.8MPa, 120℃), the reliability of the overall structure is enhanced, the problem of shell cracking caused by nut stress is solved, and ceramics are transformed from simple handicrafts and appreciation objects into precision-assembled electronic products. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Example 1:

[0016] A method for plastic injection molding bonding of a ceramic matrix composite shell includes the following steps: S1. Pre-set ceramic substrate structure: Select a ceramic shell and pre-set a positioning groove inside the ceramic shell to accommodate the plastic components, which serves as the substrate to support the appearance and structure; In this embodiment, the structural adhesive used is an industrial-grade two-component epoxy adhesive. Before applying the adhesive, anhydrous ethanol is used to wipe and clean the positioning groove of the ceramic shell and the mating surface of the plastic components to remove oil and dust. The A component (main agent) and B component (curing agent) of the AB adhesive are put into the mixing tube at a mass ratio of 10:1 and stirred thoroughly. An automated three-axis dispensing machine is used to write a dispensing program according to the path of the positioning groove, control the amount of adhesive dispensed and the coating speed, ensure uniform adhesive layer thickness, and avoid adhesive overflow. In this embodiment, the preparation process of the special high-temperature interface binder is specifically defined as follows: under nitrogen protection, hydrogen-containing polysiloxane is selected as the hyperbranching precursor and dissolved in anhydrous ethanol; the temperature of the reaction system is precisely controlled at 40°C, and vinyltrimethoxysilane is slowly added dropwise at a molar ratio of 1:1 of active groups under constant temperature stirring, and the grafting reaction is carried out for 1 hour; this step utilizes a low-temperature long-time reaction strategy to retain the stereoconfiguration of the hyperbranched structure to the maximum extent and avoids gelation caused by excessive cross-linking; Triethyl borate was added as an inorganic alkoxide monomer and water in a molar ratio of 0.5-1.5 relative to the siloxane group, and the reaction was continued for 2 hours to carry out hydrolysis and condensation. The introduction of boron was intended to form a low-melting-point borosilicate glass phase at high temperature. This liquid phase mechanism helps to wet ceramic particles and promote diffusion. Finally, the high-viscosity transparent binder was obtained by rotary evaporation under reduced pressure at 60°C. S2. Plastic component adaptation preparation: Select a plastic component. The plastic component has an integrated nut post for subsequent assembly and locking. The outline dimension of the plastic component is smaller than the size of the positioning groove. A gap of 0.5mm-1.0mm is reserved between the two to accommodate the adhesive layer and for position adjustment. In this embodiment, a sintered alumina ceramic shell is selected; physical roughening is performed using 150-mesh silicon carbide sand, with the sandblasting pressure controlled at 0.3 MPa; this mesh size abrasive can construct micron-level mechanically interlocking pits on the ceramic surface while avoiding the formation of deep cracks; subsequently, it is placed in a plasma cleaner with an argon atmosphere and a radio frequency power set to 300W for high-energy beam bombardment activation for 2 minutes; this process not only removes the organic carbon impurities adsorbed on the surface, but more importantly, it generates high-energy Al-OH active sites in situ by bombarding the Al-O bonds on the fractured surface with high-energy particles, thereby improving the wetting contact angle of the subsequent binder; S3. Adaptation and application: Mix the two-component structural adhesive at a mass ratio of 10:1 and apply it evenly to the positioning groove of the ceramic shell; In this embodiment, the binder is dissolved in anhydrous ethanol to prepare a 5% by mass slurry; the coating is applied by spraying, and the dry thickness of the coating is controlled to be 5 μm; the thinner coating design aims to reduce the amount of gas released during the debinding of organic matter; the stepped heating heat treatment is carried out at a rate of 2°C per minute to 400°C and held for 30 minutes; in this low-temperature slow pre-firing stage, the siloxane segments in the binder undergo a dehydration condensation reaction with the hydroxyl groups on the ceramic surface to form -Si-O-Al- chemical bonds, and at the same time, the organic components begin to transform into an ordered inorganic framework, constructing a defect-free nanoscale transition layer; S4. Precision Fixture Alignment and Tolerance Compensation: The plastic component is pressed into the positioning groove of the ceramic shell using a centering fixture. The physical limit of the fixture forces the center of the nut column of the plastic component to be aligned with the preset standard coordinates. At this time, the flow of structural adhesive is used to fill the gap caused by the sintering tolerance of the ceramic shell, so as to achieve independent positioning of the plastic component relative to the ceramic surface reference surface. Example 2:

[0017] This embodiment provides a plastic injection molding bonding method for a ceramic matrix composite shell, which is another specific implementation based on the technical solution of Embodiment 1, and aims to verify the temperature resistance performance of the aminosilane system and aluminum alkoxide. In S1, the hyperbranched polysiloxane or hyperbranched polysilazane precursor is selected from hydrogen-containing polysiloxane or 3-aminopropyltriethoxysilane condensate; the silane coupling agent is selected from at least one of vinyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane; and the inorganic alkoxide monomer is selected from at least one of triethyl borate and aluminum isopropoxide. In this embodiment, 3-aminopropyltriethoxysilane condensate was specifically selected as the precursor of hyperbranched polysilazane. To obtain the hyperbranched structure, the condensate was specially prepared as follows: aminopropyltriethoxysilane monomer was dissolved in anhydrous ethanol, and deionized water was added dropwise under hydrochloric acid catalysis at pH=4 for controlled hydrolysis. Subsequently, it was polycondensed at 60°C for 8 hours. By controlling the degree of hydrolysis and the polycondensation time, the molecular chains were induced to grow in three-dimensional space to obtain a hyperbranched aminopropyl polysiloxane with a branching degree of about 0.65. This structure contains a large number of terminal amino active sites. Dissolve it in isopropanol, control the reaction temperature at 45℃, add 3-glycidoxypropyltrimethoxysilane dropwise at a molar ratio of active groups of 1:1.05, and react for 1.5 hours; then add aluminum isopropoxide as an inorganic alkoxide monomer and continue the reaction for 2.5 hours; the introduction of aluminum-oxygen bonds significantly improves the high temperature resistance and chemical stability of the interface layer, making it more suitable for high temperature conditions. In step S2, the physical roughening treatment is carried out by sandblasting with 150-200 mesh silicon carbide or alumina sand at a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation is carried out in an argon or argon-hydrogen mixed atmosphere with a radio frequency power of 300-500 W and a treatment time of 2-4 minutes. In this embodiment, a zirconia ceramic shell is selected; physical roughening is performed using 160-mesh alumina sand at a sandblasting pressure of 0.35 MPa; plasma activation is performed using an argon-hydrogen mixed atmosphere at a radio frequency power of 350 W for 2.5 minutes; the addition of hydrogen creates a reducing atmosphere, which helps to remove stubborn oxide impurities on the surface and further enhances the surface energy. In step S3, the solvent of the binder slurry is anhydrous ethanol, and the mass fraction of the binder is 5%-15%; the dry thickness of the coating is controlled to be 5-20μm; the core of this embodiment is to use the flexible adhesive layer curing process to absorb the rigid ceramic sintering error; after the ceramic shell is sintered at high temperature, its dimensional shrinkage rate is difficult to control precisely, and there is usually a tolerance of about ±0.5%. If the plastic parts are assembled directly by mechanical interference fit, it is very easy to cause ceramic cracking or nut column position displacement. Step S4 employs the principle of suspension positioning: the ceramic shell coated with adhesive is placed on the bottom mold, and a high-precision centering fixture is used to adsorb the plastic component; the fixture is positioned according to the surface reference plane of the ceramic shell, forcibly moving the center of the nut column of the plastic component to the theoretical coordinate position; at this time, the plastic component is not in direct rigid contact with the ceramic groove wall, but is suspended in the uncured adhesive; the adhesive automatically fills the irregular gaps caused by ceramic deformation. Example 3:

[0018] This embodiment provides a plastic injection molding bonding method for ceramic matrix composite shells, which uses a composite coupling agent and moderate process parameters to achieve an optimized balance of interfacial properties. In step S1, the preparation process is as follows: the precursor is dissolved in anhydrous ethanol or isopropanol, the reaction system temperature is controlled at 40-60℃, and constant temperature stirring is carried out; silane coupling agent is slowly added dropwise at a molar ratio of active groups of 1:1 to 1:1.2, and the reaction is carried out for 1-3 hours; then inorganic alkoxide monomer and catalytic amount of water are added, and the reaction is continued for 2-4 hours for hydrolysis and condensation; finally, the solvent and low-boiling substances are removed by vacuum distillation at 60-80℃ to obtain a viscous binder; In this embodiment, hydrogen-containing polysiloxane was selected as the precursor and dissolved in anhydrous ethanol; the reaction temperature was 50°C, and a mixture of vinyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane was added dropwise at a molar ratio of 1:1.1 for active groups, and the reaction was carried out for 2 hours; then a mixture of triethyl borate and aluminum isopropoxide was added, and the reaction was continued for 3 hours; the boron-aluminum co-doping strategy aims to adjust the thermal expansion coefficient of the interface layer so that it is between the substrate and the newly formed layer, thus playing a stress buffering role in the gradient; In step S2, the physical roughening treatment is carried out by sandblasting with 150-200 mesh silicon carbide or alumina sand at a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation is carried out in an argon or argon-hydrogen mixed atmosphere with a radio frequency power of 300-500 W and a treatment time of 2-4 minutes. In this embodiment, a silicon nitride ceramic shell is selected; physical roughening is carried out using 175-mesh silicon carbide sand with a sandblasting pressure of 0.4 MPa; plasma activation is carried out in an argon atmosphere with a radio frequency power of 400 W for 3 minutes; for the relatively inert surface of silicon nitride, a high power density is a necessary condition for activating the Si-N bonds on the surface. In step S3, the solvent for the binder slurry is anhydrous ethanol, and the mass fraction of the binder is 5%-15%; the dry thickness of the spray coating is controlled to be 5-20μm; the specific process of the stepped heating heat treatment is: heating to 400-500℃ at a rate of 2-5℃ per minute and holding at that temperature for 30-60 minutes for pre-firing. In this embodiment, the binder mass fraction is 10%, and the dry coating thickness is controlled at 12 μm. The pre-firing process is as follows: the temperature is increased to 450°C at 4°C / min and held for 45 minutes. The combination of this thickness and the pre-firing process creates a reaction pool of sufficient thickness at the interface, providing a sufficient source of material for subsequent element diffusion. Example 4:

[0019] This embodiment provides a plastic injection molding bonding method for ceramic matrix composite shells, which focuses on higher activation energy and thicker interface layer, and is suitable for large-size or high-stress components. In step S1, the preparation process is as follows: the precursor is dissolved in anhydrous ethanol or isopropanol, the reaction system temperature is controlled at 40-60℃, and constant temperature stirring is carried out; silane coupling agent is slowly added dropwise at a molar ratio of active groups of 1:1 to 1:1.2, and the reaction is carried out for 1-3 hours; then inorganic alkoxide monomer and catalytic amount of water are added, and the reaction is continued for 2-4 hours for hydrolysis and condensation; finally, the solvent and low-boiling substances are removed by vacuum distillation at 60-80℃ to obtain a viscous binder; In this embodiment, 3-aminopropyltriethoxysilane condensate was selected. This precursor was prepared using a quasi-one-step method to ensure a hyperbranched configuration: aminopropyltriethoxysilane was added dropwise to an excess of acidic aqueous alcohol solution under vigorous stirring to inhibit cyclization and promote the growth of a three-dimensional network. After neutralization, extraction, and vacuum drying, a high-viscosity hyperbranched condensate was obtained. It was dissolved in isopropanol at a reaction temperature of 55°C, and 3-glycidyl etheroxypropyltrimethoxysilane was added dropwise at a molar ratio of 1:1.15 of active groups, and the reaction was carried out for 2.5 hours. Aluminum isopropoxide was added, and the reaction was carried out for 3.5 hours. The high degree of grafting and condensation reaction increased the molecular weight of the prepolymer, which is beneficial for the formation of a high-strength inorganic framework. In step S2, the physical roughening treatment is carried out by sandblasting with 150-200 mesh silicon carbide or alumina sand at a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation is carried out in an argon or argon-hydrogen mixed atmosphere with a radio frequency power of 300-500 W and a treatment time of 2-4 minutes. In this embodiment, a zirconia ceramic shell is selected; physical roughening is performed using 190-mesh alumina sand at a sandblasting pressure of 0.45 MPa; plasma activation is performed using an argon-hydrogen mixed atmosphere at a radio frequency power of 450 W for 3.5 minutes; the strong physical and chemical activation effects maximize the surface roughness and active site density of the substrate. In step S3, the solvent for the binder slurry is anhydrous ethanol, and the mass fraction of the binder is 5%-15%; the dry thickness of the spray coating is controlled to be 5-20μm; the specific process of the stepped heating heat treatment is: heating to 400-500℃ at a rate of 2-5℃ per minute and holding at that temperature for 30-60 minutes for pre-firing. In this embodiment, the binder mass fraction is 12.5%, and the dry coating thickness is controlled at 16 μm. The pre-firing process is as follows: the temperature is increased to 475°C at 4.5°C / min and held for 50 minutes. The thicker interface layer can effectively absorb and dissipate external impact energy, providing excellent stress buffering capacity. Example 5:

[0020] This embodiment provides a plastic injection molding bonding method for a ceramic matrix composite shell, using the upper limit of process parameters to explore the ultimate performance of interfacial bonding strength; In step S1, the preparation process is as follows: the precursor is dissolved in anhydrous ethanol or isopropanol, the reaction system temperature is controlled at 40-60℃, and constant temperature stirring is carried out; silane coupling agent is slowly added dropwise at a molar ratio of active groups of 1:1 to 1:1.2, and the reaction is carried out for 1-3 hours; then inorganic alkoxide monomer and catalytic amount of water are added, and the reaction is continued for 2-4 hours for hydrolysis and condensation; finally, the solvent and low-boiling substances are removed by vacuum distillation at 60-80℃ to obtain a viscous binder; In this embodiment, a hydrogen-containing polysiloxane was selected and dissolved in anhydrous ethanol; the reaction temperature was 60°C, and vinyltrimethoxysilane was added dropwise at a molar ratio of 1:1.2 of active groups, and the reaction was carried out for 3 hours; triethyl borate was added, and the reaction was carried out for 4 hours; the long-term high-temperature reaction ensured the high cross-linking and maturation of the sol network, laying the foundation for the formation of a dense ceramic phase; In step S2, the physical roughening treatment is carried out by sandblasting with 150-200 mesh silicon carbide or alumina sand at a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation is carried out in an argon or argon-hydrogen mixed atmosphere with a radio frequency power of 300-500 W and a treatment time of 2-4 minutes. In this embodiment, an alumina ceramic shell is selected; physical roughening is performed using 200-mesh silicon carbide sand with a sandblasting pressure of 0.5 MPa; plasma activation is performed using an argon atmosphere with a radio frequency power of 500 W for 4 minutes; the treatment of the limiting parameters completely removes any possible weak boundary layers. In step S3, the solvent for the binder slurry is anhydrous ethanol, and the mass fraction of the binder is 5%-15%; the dry thickness of the spray coating is controlled to be 5-20μm; the specific process of the stepped heating heat treatment is: heating to 400-500℃ at a rate of 2-5℃ per minute and holding at that temperature for 30-60 minutes for pre-firing. In this embodiment, the binder mass fraction is 15%, and the impregnation control dry thickness is 20μm; the pre-firing process is: heating to 500℃ at 5℃ / min and holding for 60 minutes; the thorough pre-firing treatment completely removes the organic volatiles and prevents bubbling defects during the final high-temperature sintering. Although the energy consumption is high, it ensures the perfect density of the interface. Example 6:

[0021] This embodiment provides a ceramic matrix composite shell with a special appearance effect and its preparation method; the ceramic shell is a cracked series ceramic keycap or a ship shell used in electronic keyboards; before performing the surface activation treatment in step S2, an ice crack glaze layer with irregular distribution characteristics is formed on the surface of the ceramic matrix through a specific sintering process. Because of the microscopic physical gaps in the cracked glaze surface, traditional physical bonding easily generates bubbles or stress concentration points at these gaps. This embodiment uses a boron / aluminum high-temperature interface binder prepared in step S1. This binder has excellent permeability and can penetrate into the micropores of the glaze cracks. The specific bonding process is as follows: Ceramic substrate preparation: Select a ceramic hull with cracked glaze and reserve an assembly groove at the bottom; Surface modification: Plasma activation is performed on the bonding surface of the groove, and the pores are sealed and modified using a binder. After pre-firing at 450℃, dense inorganic anchoring points are formed deep in the cracks. Precision assembly: Using AB glue with a 10:1 ratio, and with the help of a 1.0mm feeler gauge for alignment, the plastic inner liner with the standard nut column is pressed into the ceramic groove. Curing: Hold at 120℃ and 0.8MPa for 120 seconds; This method utilizes the microscopic repair effect of interfacial binders on cracks, which not only achieves strong adhesion between ceramics and plastics, but also enhances the structural stability of the cracked glaze layer, preventing the glaze from peeling off when the keycap is struck or the shell is subjected to stress.

[0022] Comparative Example 1: This comparative example provides a method for preparing a ceramic matrix composite shell. Compared with Example 3, the only difference is that steps S1 and S3 are omitted, that is, a high-temperature interface binder is not used, and the interface layer is not constructed or pre-fired. Specifically, the activated ceramic matrix after step S2 is directly pressed into the ceramic powder, and then co-sintered according to step S4. This comparative example aims to verify the necessity of the interface binder. Due to the lack of an interface transition layer, the matrix and the newly added ceramic layer rely only on physical contact and limited solid-phase diffusion. There are micro gaps at the interface, and the bonding mechanism is simple and weak.

[0023] Comparative Example 2: This comparative example provides a method for preparing a ceramic matrix composite shell. Compared with Example 3, the only difference is that: no boron- or aluminum-containing inorganic alkoxide monomers are added in step S1; that is, the prepared interface agent is only modified polysiloxane, lacking the key inorganic components for generating high-temperature ceramic phases; this comparative example aims to verify the effect of inorganic alkoxide doping on interface density; during the high-temperature sintering process in step S4, the silica skeleton remaining after the thermal decomposition of the pure organosilicon network is relatively loose, and lacks the liquid phase wetting effect generated by boron / aluminum element fluxing, resulting in insufficient interface density.

[0024] Comparative Example 3: This comparative example provides a method for preparing a ceramic matrix composite shell. Compared with Example 3, the only difference is that the high-energy beam bombardment activation treatment in step S2 is omitted, and only physical roughening is performed. This comparative example aims to verify the contribution of plasma activation to the coating adhesion. The organic contaminants remaining on the ceramic surface and the lack of high-energy hydroxyl sites lead to a decrease in the wettability and chemical grafting rate of the interfacial binder on the ceramic surface in step S3, resulting in a decrease in the coating adhesion after pre-firing, which ultimately affects the overall integrity of co-sintering.

[0025] Comparative Example 4: This comparative example provides a method for preparing a ceramic matrix composite shell. Compared with Example 3, the only difference is that the step-heating heat treatment pre-firing in step S3 is omitted, and the matrix coated with wet binder is directly co-sintered in step S4. This comparative example aims to verify the importance of the step-by-step debinding process. Because the binder was not pre-fired and debinded, a large amount of solvent and organic components in the binder volatilized violently in the early stage of sintering, resulting in a large number of pores and microcracks at the interface, which seriously damaged the structural integrity of the composite material.

[0026] Verification experiment: To verify the effectiveness of the plastic injection molding bonding method for a ceramic matrix composite shell of the present invention, performance tests were conducted on the samples prepared in Examples 1-5 and Comparative Examples 1-4. The test items included shear strength, air tightness, and thermal shock performance.

[0027] Testing standards: Shear strength: Tested according to ASTM D905 standard using a universal testing machine with a loading speed of 1 mm / min. Ten samples were tested for each group and the average value was taken. Air tightness: Leakage rate was tested using a helium mass spectrometer (ZQJ-530) at a pressure difference of 0.1 MPa. The criterion for judgment was a leakage rate <1×10⁻ 9 Pa·m³ / s is acceptable; Thermal shock performance: The sample was frozen at -40℃ for 30 minutes and then transferred to a 150℃ oven for 30 minutes. This was one cycle. After 100 cycles, the interface was observed for microcracks using a scanning electron microscope.

[0028] Data table

[0029]

[0030] As can be seen from the test results in Table 1, the shear strength of Examples 1-5 prepared by the method of the present invention is significantly higher than that of the comparative examples, and the air tightness reaches an extremely high level. This indicates that the hyperbranched structure and boron / aluminum inorganic components introduced by the special high-temperature interface binder in step S1 successfully constructed a transition layer with both chemical bonding and inorganic framework in situ during the pre-calcination stage of S3. Specifically, comparing Example 3 with Comparative Example 1, it can be seen that the introduction of the interface binder increased the shear strength from 12.4 MPa to 48.2 MPa, proving that the triple synergistic mechanism of chemical bonding + mechanical interlocking + diffusion bonding is far superior to simple physical contact. Comparing Example 3 with Comparative Example 2, although the pure organosilicon system lacking boron / aluminum can form a certain connection, the residual silica skeleton is porous and loose due to the lack of liquid phase sintering mechanism, resulting in a decrease in air tightness by 3 orders of magnitude. This confirms the key role of inorganic alkoxide doping in achieving interface densification. Furthermore, comparing Example 3 and Comparative Example 4, the sample without S3 pre-firing treatment had the worst air tightness. This is because the pore channels left by the violent volatilization of organic matter penetrated the interface layer. In contrast, Example 3 achieved an orderly transformation from organic to inorganic through step-heating pre-firing, effectively avoiding structural defects. Example 3 remained intact after thermal shock, indicating that the boron-aluminum co-doped multiphase ceramic structure effectively relieved thermal stress and achieved dense metallurgical bonding.

[0031] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for plastic injection molding bonding of a ceramic matrix composite shell, characterized in that, Includes the following steps: S1. Pre-set ceramic substrate structure: Select a ceramic shell and pre-set a positioning groove inside the ceramic shell to accommodate the plastic component, which serves as the substrate to support the appearance and structure; S2. Plastic component adaptation preparation: Select a plastic component, which integrates a nut post for subsequent assembly and locking, and the outline dimension of the plastic component is smaller than the size of the positioning groove, with a gap of 0.5mm-1.0mm reserved between them to accommodate the adhesive layer and for position adjustment; S3. Adaptation and application: Mix two-component structural adhesive at a mass ratio of 10:1 and apply it evenly to the positioning groove of the ceramic shell; S4. Precision fixture alignment and tolerance compensation: The plastic component is pressed into the positioning groove of the ceramic shell using a centering fixture. The physical limit of the fixture forces the center of the nut column of the plastic component to be aligned with the preset standard coordinates. At this time, the flow of structural adhesive is used to fill the gap caused by the sintering tolerance of the ceramic shell, so as to achieve independent positioning of the plastic component relative to the ceramic surface reference surface. S5. Pressure Holding and Curing: Place the assembled workpiece in a heating and pressure holding device and maintain it at a temperature of 120℃ and a pressure of 0.8MPa for 120 seconds until the adhesive is completely cured.

2. The plastic injection molding bonding method for a ceramic matrix composite shell according to claim 1, characterized in that, include: The ceramic outer shell has a positioning groove on its inner surface; A plastic inner liner is embedded in the positioning groove, and one or more nut posts are provided on the plastic inner liner; A structural adhesive layer is used to fill the space between the ceramic outer shell and the plastic inner liner; The positional accuracy of the nut center of the plastic inner liner relative to the surface reference plane of the ceramic outer shell is independent of the sintering tolerance of the ceramic outer shell and is compensated and corrected by the thickness of the cured structural adhesive layer.

3. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, The ceramic shell is a ceramic hull structure that serves as a PCB inner liner for electronic products. The outer surface of the ceramic hull has ice crack or natural crazing texture structure formed by sintering.

4. The plastic injection molding bonding method for a ceramic matrix composite shell according to claim 1, characterized in that, In step S3, the two-component structural adhesive is a high-temperature resistant epoxy resin AB adhesive, and its formulation ratio is 10:1 by mass of component A to component B. The adhesive is applied by an automated dispensing machine for trajectory coating.

5. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, In step S4, the centering fixture is used in conjunction with a feeler gauge to control the gap. The feeler gauge has a thickness of 0.5mm-1.0mm and is used to ensure that the plastic components are evenly spaced around the ceramic groove.

6. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, In step S2, the physical roughening treatment is carried out by sandblasting with 150-200 mesh silicon carbide or alumina sand at a sandblasting pressure of 0.3-0.5 MPa; the high-energy beam bombardment activation is carried out in an argon or argon-hydrogen mixed atmosphere with a radio frequency power of 300-500 W and a processing time of 2-4 minutes.

7. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, In step S5, the specific parameters of the pressure holding and curing process are as follows: the air pressure is set to 0.8 MPa, the heating temperature is kept constant at 120°C, and the pressure holding time is 120 s; the pressure is applied to the surface of the plastic component by a pneumatic clamp to ensure that the adhesive layer is dense and free of air bubbles.

8. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, In step S4, the heating and pressure holding equipment adopts a programmed heating method, heating to the pressure holding temperature at a rate of 2-5℃ / min, and then naturally cooling after curing.

9. The method for plastic injection molding bonding of a ceramic matrix composite shell according to claim 1, characterized in that, In step S4, the protective atmosphere is argon or nitrogen.

Images