IIT Jodhpur
Ph.D. Thesis Work of Rakesh Joshi

Title of Thesis
Experimental Investigation on Development and Structural Integrity Assessment of Glass to Metal Joint

About Candidate
  Rakesh Joshi graduated in Mechanical Engineering from Punjab Technical University, Jalandhar in 2008. He subsequently obtained M.E in (CAD/CAM and Robotics) from Thapar University, Patiala in 2010.  He carried out doctoral research under supervision of Dr. Rahul Chhibber. He has teaching experience of four years. 
Summary of the work
The joining of glass with metal plays an important role in various applications including vacuum tube, solid oxide fuel cell, electronics component and parabolic trough receiver tube (PTRT). The presented research is focused on the development of novel glass-metal joint for PTRTs. The initial aim of present investigation was to select a suitable glass-metal joint combination on the basis of wettability, surface roughness, pre-oxidation time, microstructural and X-ray diffraction studies [1-2]. Later, an unmatched glass-metal joint between borosilicate glass and austenitic stainless steel SS 304 was developed after selecting the suitable glass-metal joint combination.  40SiO2-54B2O3-4Na2O-2Al2O3 material was used as the glass sealant to join the SS304 metal ring and borosilicate glass tube. The chemical compositions of glass sealant were investigated by changing SiO2/B2O3 ratio by using statistical design of experiment approach for SiO2-Al2O3-B2O3-Na2O system [3]. The effect of SiO2/B2O3 ratio in glass sealant on wettability, glass transition temperature (Tg), crystallization temperature (Tc), thermal conductivity, adhesion and density were studied [4]. The fabricated joint was subjected to different environmental condition and the degradation of the joint was studied over the period of time. The residual stresses generated in the joint after a thermal cycling for 50 cycles were measured with the help of photo-elastic technique. The joint is subjected to different thermal cycling temperatures i.e. 150 °C, 200 °C and 250 °C and also subjected to open environment and water for approximately 200 hours. The thermal cycling result revealed that the glass-metal joint specimen in water degraded much faster as compared to the specimen exposed to atmosphere.

1) Rakesh Joshi, Rahul Chhibber, “Development and Interface Characterization of Unmatched Glass-Metal Joint” Journal of Manufacturing Process (Elsevier) (2018), 31, 787–800.

2) Rakesh Joshi, Rahul Chhibber, "High Temperature Wettability Studies for the Development of Unmatched Glass-Metal Joints in Solar Receiver tube” Renewable Energy (Elsevier) (2018), 119, 282-289.

3) Rakesh Joshi, Rahul Chhibber, “Design and Development of SiO2-Al2O3-B2O3-Na2O Based Glass Sealant for the Glass-Metal Joining Application” Ceramic International (Elsevier) (2018), Volume 44, Issue 16, Pages 19084-19098.

4) Rakesh Joshi, Rahul Chhibber, ”Effect of SiO2/B2O3 Ratio on the Thermophysical and Wetting Properties of Borosilicate Glass Sealant for Glass-Metal Joint” Journal of Materials Processing Technology, (Elsevier) (2018), 259, 186-194.