CeO_2对渗Si层组织和耐磨性能的影响

Effect of addition of CeO_2 on microstructure and wear properties of siliconzied coatings

采用料浆包渗法,以SiO2粉为Si源,纯Al粉为还原剂,NaF和NH4Cl作为复合活化剂,Al2O3为惰性添加剂,蛋白质(鸡蛋清)为粘结剂,在Cu表面预先镀Ni层随后900℃、12 h表面渗Si,制备渗Si层。分别研究了CeO2和Al粉含量对渗Si层组织和摩擦性能的影响。结果表明:当铝粉含量20%时,CeO2含量由3%增加到6%,渗层组织为Ni2Si+NiSi相;当CeO2含量6%时,铝粉含量由20%增加到30%,渗层组织变化过程:Ni2Si+NiSi→NiAl→Ni2Al3相,包渗过程由渗硅向渗铝转变;两种渗层的最小摩擦系数都约为纯铜的1/5。

A layer of electroplating nickel was deposited on copper specimens. Subsequently, these electroplated specimens were siliconized at 900 ℃ for 12 h by slurry pack cementation process. A slurry pack cementation mixture was composed of SiO： used as siliconizing source, pure A1 powder as reducer, a dual activator of NaF ＋ NH4C1 and albumen （egg white） as cohesive agent. The effect of CeO2 and A1 content on microstructure and friction property of the siliconized coatings was studied. The results show that the microstructure of the coating consists of the phase of Ni2Si ＋ NiSi by increasing the CeO2 content from 3% to 6% in the mixture powder with 20% A1 powder, and the microstructure of coatings is changing from Ni2 Si ＋ NiSi to NiA1 and finally to Ni2 A13 phase with the increasing the A1 content from 20% to 30% in the mixture powders with 6% CeO2 , at the same time, the process is changing from mainly siliconizing to aluminizing. The minimum friction coefficient of the two siliconized coatings is about 1/5 of that of pure copper.