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Tuesday, April 1, 2025

ZrO₂-coated diamond composites,

Common methods for preparing diamond/aluminum matrix composites include stirring casting and infiltration casting techniques. During these processes, liquid aluminum interacts with diamond, resulting in the formation of the Al₄C₃ phase. This phase is hygroscopic and reacts with water to produce CH₄ and Al(OH)₃, which weakens the bonding between diamond and the aluminum matrix, compromising the composite’s mechanical properties and thermal expansion performance.

ZrO₂-coated diamond composites, however, exhibit a well-bonded, flat interface without cracks, voids, or Al₄C₃ formation. The ZrO₂ coating prevents direct contact between the diamond and aluminum melt, thus inhibiting Al₄C₃ formation. This results in a tensile strength increase of ZrO₂@diamond composites to 200 MPa, a 10.8% improvement over uncoated composites. Furthermore, the linear expansion coefficient and dimensional change rate of ZrO₂-coated diamond composites are lower than those of uncoated diamond composites, indicating enhanced interface bonding and better control of thermal expansion.

The ZrO₂ coating is applied to diamond particles using evaporation crystallization, with various thermal decomposition temperatures and durations examined for their effects on the coating. The results show that a smooth, uniform ZrO₂ coating is achieved at a thermal decomposition temperature of 600°C with a 2-hour holding time. While noticeable voids are observed at the interface of uncoated diamond composites, the ZrO₂-coated diamond composites feature a uniform, well-bonded interface free from cracks, voids, or Al₄C₃ formation.

Overall, the ZrO₂ coating significantly improves the tensile strength and thermal stability of diamond/aluminum composites, demonstrating its effectiveness in enhancing material performance.

Diamond Etching Enhances the Thermal Shock Resistance of Dia/Cu Composites

Diamond Etching Enhances the Thermal Shock Resistance of Diamond/Copper Composites

Diamond/copper (Dia/Cu) composites are highly promising materials due to their exceptional thermal conductivity (TC) and adjustable coefficient of thermal expansion (CTE). However, conventional Dia/Cu composites are susceptible to thermal shock due to CTE mismatches, which induce fatigue and degradation.

In advanced manufacturing and powder metallurgy, diamond surface metallization is commonly employed to enhance thermal conductivity and wear resistance. Tungsten is often selected as a coating material due to its high intrinsic TC and low solubility in copper. While traditional diamond surface treatments improve thermal conductivity, they fail to address the critical issue of poor thermal shock resistance. This limitation arises from the significant CTE disparity between the reinforcement and the matrix, leading to thermal stress at the interface. When stress exceeds a critical threshold, interfacial damage occurs, increasing thermal resistance and reducing overall conductivity. Enhancing the thermal shock resistance of Dia/Cu composites is essential for broader applications and remains a key research focus.

By employing an etching process, the interface morphology of Dia/Cu composites was transformed from a smooth to a rough, tortuous structure. This modification effectively suppressed crack propagation, significantly improving the material’s thermal shock resistance.

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Complex Geometry in DiaSiC? No Concerns—Additive Manufacturing of Nano-Diamond Silicon Carbide Composites is Now Feasible

The increasing demand for advanced systems across various industries, including metrology, semiconductors, and tool manufacturing, necessitates components with complex geometries and enhanced material properties. Traditionally, ceramic components have been fabricated using processes such as casting and silicon infiltration. However, these methods impose significant geometric constraints, often requiring post-processing techniques such as milling to achieve intricate designs. This approach involves the removal and disposal of excess material, which is particularly inefficient when working with rare and costly materials and super hard materials like Silicon Carbide and diamond in this case.

Recent advancements now enable the additive manufacturing of Nano-DiaSiC through 3D printing technology. Furthermore, the material’s properties—such as thermal conductivity, stiffness, hardness, abrasion resistance, and thermal expansion—can be precisely tailored by incorporating diamond particles, offering superior performance for high-precision applications.