Rong Tu,Yijun Xu,Xiaoping Guo,Yibing Su,Yuzhe Han,Qizhong Li,Meijun Yang,Song Zhang,Takashi Goto
The incorporation of t-ZrO 2 into α-Al 2 O 3 matrix is a widely established method for enhancing the mechanical properties of ceramic materials, i.e. , zicornia toughened alumina (ZTA). In this study, acetylacetonate zirconium and acetylacetonate yttrium were thoroughly mixed with α-Al 2 O 3 powder and then calcined to achieve a uniform dispersion of organometallic-derived tetragonal zirconia polycrystal (TZP) particles in nano-size onto α-Al 2 O 3 , forming a composite powder. The TZP particle size increased from 8 to 39 nm with increasing calcination temperature from 600 to 1000 °C. The TZP nanoparticles coated α-Al 2 O 3 powder was sintered by spark plasma sintering (SPS) to obtain ZTA ceramics. TZP is embedded in the face-centered cubic skeleton formed by α-Al 2 O 3 and restricts grain growth to each other. The highest hardness and toughness, i.e. , 18.81 GPa and 10.31 MPa m 1/2 , of the ZTA ceramics was achieved at 1400 °C by using the composite powder calcined at 600 °C.
Xiao-yu Zhang,Min Xu,Sheng-zhu Cao,Wen-bo Chen,Wen-yao Yang,Qin-yu Yang
Diamond/copper composite has been considered as one of the next generation thermal management materials. Interfacial modification is an essential means of ameliorating interface wettability and bonding of diamond/copper composite for improving its thermal conductivity . In the present work, Diamond/copper composite was manufactured by using spark plasma sintering (SPS) technology with 60% volume fraction of diamond mixed with 40% volume fraction of copper power, chromium powder (0.7 wt%) and scandium oxide powder (0.21 wt%). A series of material analysis methods were used to characterize the microstructure, interfacial layer , phase compositions and distributions of Diamond/copper composite. The total and partial electron density of states (DOS) for Diamond-Cr-Sc 2 O 3 interfacial model was investigated by means of first-principles calculations from CASTEP modules. The results showed Sc 2 O 3 made a 5–20 nm well-arranged and uniformly distributed interfacial chromium carbide layer in the interface region, which played a critical role in increasing the amount of reactive interfacial bonding and decreasing defect. The addition of Sc 2 O 3 brought the increasing number of heat transfer carriers at the interface and made the interface energy system more stable. The obtained diamond/copper composite exhibited that the wettability between diamond particles and copper was effectively improved. The thermal conductivity of diamond/copper is 872 W/(m·K) and the possible reasons for doping rare-earths Sc 2 O 3 to improve the thermal conductivity were discussed.
危险品化学品经营许可证（带存储）