Prevention of Soldering in High Pressure Die Casting Dies Using Aluminum Iron Oxide Surface Treatment

摘要

The application of surface engineered oxide layers to prevent soldering in high pressure die casting was demonstrated using a specially designed die with removable core pins and Al-11Si-3Cu casting alloy. Soldering is an interaction between the die and the casting alloy that results in the formation of intermetallic phases and adherence of the casting to the die. H13 tool steel was treated by both steam-tempering and gas oxidation to produce compact iron oxide layers. These oxide layers act as a barrier between die steel/casting alloy and prevented the formation of the intermetallic phases associated with soldering. These treatments can be applied at relatively low temperatures and to large areas of the dies. In addition, these processes are very cost effective compared to other coating processes such as physical vapor deposition (PVD), or thermo-reactive diffusion (TRD) coatings. Protective aluminium oxide layers were also investigated for their ability to prevent soldering. Incoloy MA956 steel containing 4.5wt. percent aluminium, oxidized in air at 1100°C, produced a compact oxide layer with α-alumina (Al2O3) structure that prevented the formation of intermetallic phases between the die steel and the casting alloy.