Severe-area black-face and concave scar often appear in surface of the investment castings
especially stainless steel castings
using shell mold made of ZrO2 as face layer and kaolinite refractory as back layer
which is severely detriment to the quality of the investment castings. Chemical properties and formation of defect position have been analyzed by energy diffusion analyzer based on worksite investigation. It is revealed that surface scar in the castings is remarkably relevant to the ink-point in shell-mold
and the blackface is composed of spinel complicated compound
which is created by reaction between Fe2O3 in face-layer and different metal oxidizer from oxidation on surface of castings. Based on above mentioned analysis
the counter-measures eliminating these defects were expounded.
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology
AECC Beijing Institute of Aeronautical Materials
School of Materials Engineering, Shanghai University of Engineering Science
Shanghai Key Laboratory of Advanced High Temperature Materials and Precision Forming, Shanghai Jiaotong University