渗剂中铝粉含量对Cu基Ni镀层表面Cr-Al渗层组织和性能的影响

为了提高铜金属表面硬度和耐磨性,在铜表面预先镀镍,然后对镍镀层进行渗cr,Al,制备Cr-Al渗层.研究了渗剂中铝粉含量对其微观组织、显微硬度和耐磨性的影响.结果表明:当渗剂中铝粉含量在5%～20%(质量分数,下同)范围,渗层组织为Ni(Cr,Al)固溶体,晶面(200)出现明显的择优生长,显微硬度从HV170增加到H...

Influences of Al Content in Packing on Microstructure and Properties of Cr-Al Coating on Cu Substrate Electrodeposited Nickel Layer

The low hardness and poor wear resistance of pure copper result in the less effective use in metallurgical application.In order to increase the microhardness and wear resistance,the pure copper surface with the electro-deposited nickel layer was chromized-aluminized by slurry packing cementation process,and then Cr-Al coating was formed on the surface of Ni plating.The effects of Al powder content on microstructure,microhardness and wear resistance were investigated.The results showed that the phase of coating,which was mainly consists of a solid solution Al and Cr in Nickel,have a preferred orientation in crystal plane(200).As the mass fraction of Al powder increased from 5% to 20%,the microhardness of coating increase gradually from HV 170 to HV 200,and friction coefficient decreases from 0.55 to 0.35.However,when the mass fraction of Al powder was about 25%,the coating with microhardness of 970HV and the friction coefficient of 0.25 was composed of the main phase NiAl and a small amount of Ni2Al3 phase.As a result,the pack process was changed from the chromizing-base to aluminizing-base as the Al powder content increasing.