Agent for reducing conversion film overall friction coefficient for trivalent chromate treating solution, trivalent chromate treating solution and method for production thereof, and trivalent chromate conversion film reduced in overall friction coefficient and method for production thereof

Abstract

It is an object of the present invention to provide a conversion film obtained by contacting a treating solution based on trivalent chromium with zinc or zinc alloy plating layers, which film does not contain hexavalent chromium, which film has corrosion resistance identical to that of the conversion film obtained by the conventional chromate treatment based on hexavalent chromium, and furthermore which has an overall friction coefficient identical to or lower than that of the conventional hexavalent chromate conversion film. The present invention also provides an agent for reducing a conversion film overall friction coefficient for a trivalent chromate treating solution, which agent contains a quinoline based compound or its derivative.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a technique for reducing an overall friction coefficient in a hexavalent chromium free and corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers, in which fastening capacity is required. More specifically, the present invention relates to an agent for reducing a conversion film overall friction coefficient for a trivalent chromate treating solution, a trivalent chromate treating solution for reducing the overall friction coefficient of a trivalent chromate conversion film and a method for producing thereof, as well as a trivalent chromate conversion film reduced in an overall friction coefficient and a method for production thereof. [0003] 2. Description of the Related Art [0004] As a method for preventing rusting of the surface of a metal, there has been adopted, in this industrial field, a chromate treatment containing hexavalent chromium on zi...

AI Technical Summary

Benefits of technology

[0014] According to the present invention, it is possible to produce a hexavalent chromium free and corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers, whose overall friction coefficient is reduced. The trivalent chromate conversion film obtained by this method imparts inherent additional excellent corrosion resistance to the corrosion resistance due to the zinc or zinc alloy plating itself. Moreover, because the overall friction coefficient of the conversion film is identical to or lower than that of the conventional hexavalent chromate conversion film, a bolt, nut and so on can be designed so that the fastening strength is safe. Further, because the same devices and processes used in the conventional hexavalent chromate treatment can be u

Problems solved by technology

However, the conversion film obtained by one step of the trivalent chromate treatment generally leads to