电沉积Ni－W－P－SiC复合材料的组织及结构

MICROSTRUCTURE OF Ni-W-P-SiC COMPOSITE COATING ELECTRODEPOSITED

Ｘ—射线衍射仪测定表明，当Ｎｉ—Ｗ—Ｐ—ＳｉＣ复合镀层中的磷含量大于８ｗｔ％时，镀层在镀态时呈非晶态结构；α—ＳｉＣ微粒的存在并不影响复合镀层的结构，也不参与结构的转变。热处理温度对Ｎｉ—Ｗ—Ｐ—ＳｉＣ复合镀层的组织结构有一定的影响，当温度升到３００～４００℃时，产生Ｎｉ３Ｐ粒子，起到沉淀硬化作用，因此，复合镀层的硬度最高；若继续升高温度，Ｎｉ３Ｐ粒子长大，然后集聚并粗化，导致镀层软化，硬度下降。扫描电镜证明，α—ＳｉＣ微粒在复合镀层中的分布较均匀。添加剂的加入，有利于提高复合镀层的晶化温度。

X-ray diffraction shows that the Ni-W-P-SiC composite coating is amorphous state in plating when P content of the composite coating is over 8%. The existence of α-SiC particles has no effect on the structure of the composite, and is not involved in the transition of the structure. Temperature of heat treatment has a considerable effect on the structure of the Ni-W-P-SiC composite coating.Ni3P particles are separated out and the role of precipitation hardening has played when temperature is raised to 300-400℃.Therefore, hardness of the composite reaches its peak value.Ni3P particles grow up,agglomerate and coarsen with increasing of temperature,as a result,the composite coating softens and the hardness decreases.Scanning electron microscope demonstrates that the distribution of α-SiC particles in the composite is uniform.The crystalline temperature of the composite rises when the additive is added in the bath.