The mechanical parts used in the sliders are usually applied with lubricating oils. Under the circumstances where lubricating oils cannot be used, solid lubricants are required instead. Self-lubricating alumite has a film with pores in which one of the traditional solid lubricants, like graphite, molybdenum disulfide, or Teflon resin, is directly produced.

(1) Secondary electrolytic tin as lubricant

An alumite film formed with a sulfuric acid bath and then subjected to a secondary electrolytic tin bath will have an extremely low wear coefficient. Table 1 shows the results of such a test. As is clear from the table, the films with only their pores filled with tin showed increases in the wear coefficient proportional to the number of times the pores experienced friction. Meanwhile, the film with pores over deposited with tin showed a constant wear coefficient. Thus, an anodic oxide film formed on the aluminum, a relatively soft metal, and further coated with a thin film of soft metal such as tin or cadmium provides wear resistance under low loads.

[Table 1] Wear coefficients of tin-deposited films *

*Load of 99 g, steel ball diameter of 5 mm, stroke of 10 mm, and speed of 3.9 mm/sec

(2) Secondary electrolytic deposition of MoS₂

An anodic oxide film subjected to a secondary electrolytic bath consisting mainly of ammonium molybdate is provided with pores filled with directly produced highly lubricating molybdenum disulfide (MoS₂).

(3) Electrophoretic Teflon particles

When immersed in a solution containing dispersed particles (0.5 to 5 μm) of Teflon (tetrafluoroethylene) recognized for excellent lubricity and non-adhesiveness (resistance to adhesion), an anodic oxide film-covered work piece will become an anode for electrophoresis so that the pores in the alumite will be filled with negatively charged Teflon particles. This technique is well known as the Tufram process.

(4) Wear coefficients of anodic oxide films

Fig. 1 is a summary of the wear coefficients of the anodic oxide films described above: