Environmental sensors and other bodies, together with associated lead wires, are mounted to a oxidizable substrate for high temperature applications by means of a reacted borosilicate mixture (RBM) that secures the body relative to the substrate via of an oxide interface formed between the RBM and substrate during a high temperature reaction process. An oxide interface is also formed with oxidizable bodies to provide further mounting strength. The RBM is a B.sub.2O.sub.3--SiO.sub.2 mixture, with the B.sub.2O.sub.3 portion a function of the reaction temperature and desired bonding strength and viscosity.