Process parameters influence on mechanical strength of direct bonded surfaces for both materials: Silica and Zerodur glasses

Natacha Cocheteau (1) , Aurelien Maurel-Pantel (1) , Frédéric Lebon (2) , Iulian Rosu (1) , E. Prieto (3) , Sonia Ait Zaid (4) , Isabelle Savin de Larclause (4) , Yves Salaun (5)

1 M&S - Matériaux et Structures
2 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
3 LAM - Laboratoire d'Astrophysique de Marseille
4 CNES - Centre National d'Études Spatiales [Toulouse]
5 Winlight Optics

Direct bonding is of particular interest for optical system manufacturing for spatial application. This technology is already used in terrestrial optical system manufacturing because of the very high precision of the process and complex geometries are able to bond. However, even if a first prototype already passed with success space environment test, quantification and improvement of the mechanical strength of assemblies are essential to validate the assembly's life expectancy and to validate the European Space Agency standards. So, this work proposes to study the influence of process parameters, such as roughness, relative air humidity during room temperature bonding, annealing time and temperature, on mechanical strength of an elementary mechanical structure using a double shear test procedure and cleavage tests. At the same time, the performances of fused silica and Zerodur® glasses are compared. For the process considered in this study, a parallel is made between chemical phenomena, surface roughness and mechanical strength. In the end, cleavage tests confirm the choice of the optimal process parameters and highlight a damaging phenomenon of bonded interfaces with successive re-adhesion.

Mots clés: direct bonding; mechanical strength; bonding energy; double shear test; annealing temperature; roughness; humidity; annealing time; silica glasses; Zerodur® glasses

Domaines: Mécanique des solides [physics.class-ph]; Mécanique des solides [physics.class-ph]

Natacha Cocheteau, Aurelien Maurel-Pantel, Frédéric Lebon, Iulian Rosu, E. Prieto, et al.. Process parameters influence on mechanical strength of direct bonded surfaces for both materials: Silica and Zerodur glasses. Journal of Adhesion Science and Technology, 2014, 28 (10), pp.915-934. ⟨10.1080/01694243.2013.876138⟩. ⟨hal-01007301⟩