SURFACE TREATMENT METHOD OF SCREW ROTOR FOR SCREW FLUID MACHINE AND SCREW ROTOR FOR SCREW FLUID MACHINE

摘要

PROBLEM TO BE SOLVED: To form a highly rigid coating useful in corrosion prevention, abrasion resistance, lubricity improvement or the like on a surface of a rotor part in a screw rotor for a screw fluid machine.;SOLUTION: The screw rotors 3, 4 having structures keeping rotor parts 31, 41 formed of aluminum alloys containing Si of 1 wt.% or lower on outer peripheries of rotor shafts 32, 42 are prepared. The rotor parts 31, 41 of the screw rotors 3, 4 are dipped into an electrolytic solution containing a zirconium salt and spark discharge is executed by energization by taking the rotor parts 31, 41 as anodes. The spark discharge forms a ceramic coating capable of providing high rigidity and excellent abrasion resistance and mainly having a composition of ZrO₂-Al₂O₃-MgO having lubricity on surfaces of the rotor parts 31, 41.;COPYRIGHT: (C)2010,JPO&INPIT