Mechanical and Thermo-Mechanical Protection by Alumina Sol-Gel Coatings

Abstract

ABSTRACTAlumina coatings made by the sol-gel process using aluminum sec butox-ide can be made with variable surface area and porosity by firing on dense alumina substrates in the firing range 700 to 1000 C. These coatings are found to have large (over 100 MPa) compressive stresses and to cause a small but significant strengthening of the substrates. Within this firing range the surface area decreases while both the internal stress and strengthening effect increase with increasing firing temperature. Wear rate values are high but decrease with increasing firing temperature.