Effect of Impurity Elements in Recycled Ingots on Seizure Properties of Die-Cast Cylinders made of Hypereutectic Al-Si Alloy

Abstract

<div class="section abstract"><div class="htmlview paragraph">In recent years, efforts to reduce CO₂ emissions (carbon neutrality) have accelerated worldwide. In the aluminum manufacturing industry, CO₂ emissions can be reduced by switching the raw materials of choice; from virgin ingots to recycled ingots. However, the possible characteristic change accompanying the usage of impurity-ridden recycled ingots severely limits its applications, which also limits its potential contribution to carbon neutrality. Determining how impurity elements present in recycled ingots can affect the function of manufactured components is a necessary first step towards expanding the usage of recycled ingots.</div><div class="htmlview paragraph">In this study, we aimed to apply recycled ingots to the monolithic cylinder made of hypereutectic Al-Si alloy and investigated how impurity elements in recycled ingots affect properties (especially seizure characteristic).</div><div class="htmlview paragraph">Die-cast cylinders using virgin and recycled ingots were manufactured and their properties were investigated. The elements that increased in the recycled ingots were Zn, Mn, and Ni. The effects of these elements on the seizure resistance were confirmed by reciprocating sliding test. In addition, we confirmed the differences in the compounds formed from metallographic observations and discussed the relationship between these compounds and seizure resistance using thermodynamic calculation software (Thermo-calc), among other methods.</div></div>