In order to explain the excellent tribological characteristics of Al-40Si-Cu-Mg spray coatings, influences of annealing temperature on tribological properties of the coatings are examined. The wear resistance of the coatings deteriorates with increasing annealing temperature up to 673 K, above 673 K it decreases rapidly. Meanwhile, the wear resistance of coatings before annealing is superior to that of spray coatings after annealing. This is attributed to supersaturated solid solution and rapid quenched microstructure uniformly-dispersed with sub-micron size silicon particles. After annealing, the friction coefficient of the coatings increases slowly with increasing annealing temperature up to 673 K. On the other hands, low friction of the spray coatings before annealing is obtained, since the coating is in a non-equilibrium state, which easily promotes the formation of film-like layer by tribo-chemical reactions. The formation of film-like layer consisting compound formed between silicon and oxygen is related to low friction behaviour of the coatings, and prevents the coating surface from adhering to iron and wearing the coatings. From the results obtained, it was suggested that Al-40Si-Cu-Mg sprayed coatings show low friction property caused by the formation of film-like layer and silanol formation on it.%近年，自動車の軽量化のため，アルミニウム合rn金をはじめとした軽合金の活用が注目されている．rn運動部品の軽合金の適用においては，しゆう動をrn伴うため耐摩耗性の向上が不可欠である．
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