Effects of Al addition on mechanical properties of plasma spayed Al_2O_3-AI composite coatings

摘要

In this work, Al_2O_3-Al composite coatings with different compositions (Al_2O_3-5wt.% Al, Al_2O_3-10wt.% Al and Al_2O_3-15wt.% Al) were deposited by plasma spraying. The effect of Al addition on the mechanical properties of coatings was explored in terms of microhardness, fracture toughness and sliding wear rate. An additional statistical study of Weibull analysis was carried out for further investigating the mechanical data variation. The increase in Al addition was realized to show little effects to decrease porosity of coatings. With the increase in Al addition, the microhardness of coatings decreased from 869 to 742 Hv_(0.2) along with larger fluctuation in microhardness values indicated by lower Weibull modulus (5.7-10), whereas toughness of coatings was improved ranging from 2.7 to 4.1 MPa.m~(1/2). Friction tests showed that the Al additions effectively contribute to decrease the friction coefficient of coatings sliding against steel counterpart. Among various coatings, the Al_2O_3-15wt.% Al coating exhibits lowest friction coefficient but worst wear resistance. This may arise due to its significantly decreased microhardness.