Abstract: To investigate the risk of nickel sulfide particles inducing the spontaneous breakage of tempered glass, this study introduced the concept of "equivalent critical volume expansion" and employed numerical simulation to analyze the effects of particle size, shape, and location on spontaneous breakage of tempered glass. The phase transition of nickel sulfide was modeled through thermal expansion induced by temperature increase, allowing quantitative analysis of phenomena breakage of tempered glass. Stress and temperature variations surrounding the nickel sulfide particles were examined to determine the distribution of maximum principal stress and the volume expansion of nickel sulfide particles at the onset of spontaneous breakage. The findings indicate that the risk of spontaneous breakage increases as the nickel sulfide particle moves closer to the center of tempered glass, while spontaneous breakage is nearly absent when nickel sulfide particles are located in compressive stress zones. The spontaneous breakage risk intensifies with nickel sulfide particle shapes approaching prolate spheroids, whereas in oblate spheroids, the risk must be assessed based on the orientation of the particle's major axis. For safety considerations, it is recommended that tempered glass be classified as having a high risk of spontaneous breakage when nickel sulfide particle size exceeds 0.12 mm.

Key words: tempered glass, nickel sulfide particle, glass spontaneous breakage, numerical simulation, risk evaluation, stress concentration, volume expansion