Study On The Preparation And Properties Of Wear-resistant MCPA6Composites

Casting nylon6(MCPA6) is a widely used engineering plastics, for its unique molding process and excellent comprehensive performance. But the dry friction coefficient of pure MCPA6is so high that it is hard to meet the working requirements of oil-free lubrication condition. When working under the high load, MCPA6shows bad self-lubrication and high volume abrasion rate, which limit its application to some extent. Choosing suitable fillers to fill and modify MCPA6can effectively improve the tribological and mechanical performance, and contribute to obtaining more excellent comprehensive properties of MCPA6composites.This thesis chooses the ultrafine talcum powder (Talc), liquid paraffin (LP), colloidal graphite (Gr.) and molybdenum disulphide (MoS2) and their combined system as the fillers to fill and modify MCPA6. In this paper, the friction and wear properties and mechanical properties of modified MCPA6compositematerials were mainly studied, the friction and wear mechanism of the MCPA6composites was explored, the thermal properties of MCPA6composites were discussed, and at the same time, the modified effects of various fillers on MCPA6were compared and analysed.Studying the modification effect of the four kinds of single filler on tribological performance and mechanical performance, LP had the optimal modified effect on friction coefficient, STD value and volume wear rate of MCPA6.When the content of LP was9%, the friction coefficient of the composites was0.037,which was the lowest, and STD value was only0.015and volume wear rate decreased to1.93×10-6mm3/Nm, which were reduced by84.5%,89.8%and84.5%respectively than pure MCPA6,the notched impact strength compared with MCPA6matrix changed slightly, but the tensile strength reduced by29.8%, the fracture elongation increased by22.8%.MoS2/LP, Gr./LP, Talc/LP, MoS2/Gr., Talc/MoS2and Talc/Gr were used to modify MCPA6. The results showed that MoS2/LP, Gr./LP, Talc/LP were better than the other three binary compound fillers in improving the tribological properties of MCPA6composites, which reduced the friction coefficient, STD value and volume wear rate all by more than90%.And binary composite fillers contained LP had synergy effect on the tribological and mechanical properties of MCPA6composites. The best modify effect on tribological and mechanical properties were obtained by LP-9%/MoS2-3%/MCPA6.And modified MCPA6composites still had preferable thermal stability, whose crystallization temperature, melting temperature and crystallinity were slightly higher than pure MCPA6.The results of combined fillers LP/Talc/MoS2and LP/Talc/Gr modified MCPA6revealed that, LP/Talc/Gr was more effective in the modify effect of MCPA6on tribological performance than LP/Talc/MoS2. LP-6%/Talc-3%/Gr.-3%/MCPA6achieved the lowest friction coefficient, STD value and volume wear rate, which decreased by93.8%,98%and96.7%compared with pure MCPA6, while the mechanical properties and thermal stability of the composite is relatively poor.