Abstract
Recent research has shown that copper-alloy dies sprayed with a protective steel layer can potentially replace steel dies in the pressure die casting process for the purpose of rapid heat extraction. The deposited layer is required to withstand abrasion, thermal shock, and cyclic loading, and be resistant to debonding from the copper-die substrate. This paper is concerned with an experimental investigation into the application of the HIP process to ascertain its effectiveness towards enhancing the bond strength, hardness, and densification of chrome steel coatings on a copper substrate. A particular focus of the paper is on the use of partial encapsulation coupled with the use of ceramic paper whose purpose is to transfer the loading pressure and prevent bonding between the die and the encapsulation container. It is shown in the paper that partial encapsulation is effective and can be used to HIP localized regions of a die. The ceramic paper was shown to be effective in transmitting loading and has the added advantage of providing relatively good surface finish as compared with that obtained with ceramic powder. The results of the experimental trials show reduced porosity and increased bond strength with application of the HIP process. In addition hardness values are shown to be reduced to levels typically found in traditional die-tool steels.