摘要
系统地测定和分析了由硬化剂NH4Cl、AlCl3和MgCl2所硬化的型壳的常温、高温和残留强度，并对其强度上的差异提出一些新的见解．
Systematic measurement and analysis on the strength of room-temperature and high-temperature, as well as the retained strength for mourn shells hardened resistively by agents of NH4Cl,AlCl3, and MgCl2 are performed in this paper, and some new view points about these differences in strength are proposed.
