Molecular dynamics simulation to investigate titanium metallization on sapphire for fiber optic-based pressure sensing application

Abstract

Brazing of sapphire or ceramic with metal is an essential manufacturing process for sensor and ultra-high vacuum applications. For an efficient brazing of such materials with metals, a prerequisite of metallization of sapphire with titanium (Ti) layers with good adhesion is required. In this direction, the present work is carried out to investigate the phenomena occurring at the interface of titanium–sapphire during metallization process and observe the strength of joint of sapphire with respect to Ti layer. To carry out such study, a model was constructed using molecular dynamics simulation (MDS) for both sapphire and Ti. The MDS model showed that the chemical reaction between Ti and sapphire takes place to form new chemical bonds of Ti–O, Ti–O–Al–O–Ti, and Al–O–Ti. These new bonds are much stronger than the chemical bonds of parent materials and they are the key factor for brazing of sapphire surface using Ti layer. This study shows that chemical reaction in the metallization is a spontaneous and exothermic process which increases the temperature of Ti layer by 450 K. Moreover, it is also observed that the metallization quality mainly depends on the extent of proximity between sapphire and Ti, and it is possible by surface heating up to 1,200 K. The present work is for the understanding and optimization of metallization process, which could be useful toward an efficient execution of brazing between sapphire and metal.