Study On Fabrication And Properties Of Diamond/Al Matrix Composites

It is important to dissipate the heat generated from high power electronic components to insure its regular work.Diamond/Al composites have drawn much attention for its excellent thermal physical performance.In this paper,we want to get Diamond/Al composites with high thermal conductivity which is prepared by compression molding combine with gas pressure infiltration.The influence of different diamond particle size,grade and different gas pressure infiltration process on thermal physical properties of Diamond/Al composites is discussed.The influence of diamond particles surface metallization on thermal conductivity and microstructure are studied.In addition,the environmental adaptability of Diamond/Al composites is investigated.We expect to prepare Diamond/Al composites with high thermal conductivity to meet the demand of future market.Diamond/Al composites are prepared by compression molding combine with gas pressure infiltration.The influence of different diamond particle size,grade and different gas pressure infiltration process on thermal physical properties of Diamond/Al composites is discussed.The results show that the Diamond/Al composites have a higher thermal conductivity with larger particle size and higher particle grade.Diamond/Al composites are prepared by two different diamond particles size of about 450?m and 50?m,and its thermal conductivity are 665.4 W/(m·K),thermal expansion coefficient are(2.7~4.0)×10-6/?,diamond volume fraction are 72.5%.The thermal expansion coefficient and bending strength are closely related to the diamond particle size,the smaller the diamond particle size,the lower the thermal expansion coefficient,the greater the bending strength.With the growth of the infiltration temperature and holding time,the thermal conductivity of Diamond/Al composites show the tendency of increasing first then decreased.The best infiltration temperature and holding time are 800 ? and 1 m in respectively.Mo coating is prepared on the surface of diamond particles by magnetron sputtering method.The influence of Mo coating and crystallization heat treatment on coating composition and microstructure are investigated.Experimental results show that the thickness of Mo coating with sputtering time of 9h and 12 h are about 0.8?m to 1.5?m,and with the growth of sputtering time,the roughness of the Mo coating are also increased.Crystallization heat treatment turns the Mo atoms on diamond particle from amorphous state to crystalline state.The thermal conductivity of the Diamond/Al composites reached 375.4 W/(m·K)after 9h of sputtering and 2h of heat-treatment at 800?W coating is prepared on the surface of diamond particles by reaction diffusion method.The influence of reaction time and reaction temperature on coating composition and microstructure morphology are discussed,and the thermal conductivity and microcosmic fracture morphology of Diamond/Al composites are studied,in addition,the environmental adaptability of Diamond/Al composites was investigated.With the growth of reaction time and the increase of reaction temperature,it turns from bare,incomplete coating into homogeneous continuous W coating.When the reaction time is 3h,reaction temperature is 1050?,the thermal conductivity of Diamond/Al composites is 538.6 W/(m·K).The metal coating on the surface of diamond particle has the ability to eliminate selective adhesion phenomenon and improve the interface bonding,so the Diamond/Al composites with metal coating show fewer gaps and holes in microcosmic fracture morphology.Metal coating can effectively restrain Al4C3 generated from interface reaction,which improve the stability of Diamond/Al composites in moist environment.