Possible Flash Temperatures in Slider and Recording Disk Transient Contact

Abstract

A numerical solution in two dimensions of thermal effects in steady-state sliding confirms Blok's original analysis. It is shown that for transient sliding (assuming sudden contact), surface temperatures of about 50 percent of the steady-state value are reached in one sliding width of a contact patch and 80 percent in ten widths. If voids or singularities exist close to the surface in the moving body, transient surface temperatures easily exceeding the Blok steady-state value can occur. These results are applied to asperity contact between sliders and magnetic recording disks. It is shown that temperatures exceeding several hundred degrees centigrade are quite possible, depending on asperity size and porosity of the bulk materials. Such high temperatures could lead to lubricant breakdown and head “crashes.” Suggestions are made on methods of reducing flash temperature, principally by the application of very thin coatings of high thermal capacity on the disk surface.