Role of passivating oxide films on Fe, Ni and stainless steel, and transferred film of PTFE composites in the wearing action

Abstract

The role of passivating oxide films on the stainless steel in wearing action has been studied as a function of applied potential and chloride ion concentration using a modified pin-on-disc type wear machine. Also, The growth kinetics of the passivating oxide film of nickel were investigated in the aqueous solution, and a theoretical analysis of the growth kinetics of iron has been made. Moreover, the role of the transferred films of poly tetra fluoro ethylene(PTFE) composites containing fluorinated ethylene proylene(FEP) in the wearing action has been studied using the modified pin-on-disc type machine. In chapter III, the influence of applied potential on the corrosive wear behaviour of type 304-L stainless steel in 1 N $H_2SO_4$ solution has been investigated. The corrosive wear rate increased with increasing applied potential up to 600$mV_{SCE}$, and then decreased. The corrosive wear rate $W_{CW}$ consists of three factors, viz., pure mechanical wear loss $W_{MECH}$, weight loss caused by the corrosion reaction $W_{DISS}$, and acceleratory contribution due to the presence of passivating oxide film $W_{ACC}$. The fraction of the acceleratory contribution increased with increasing applied potential up to 200$mV_{SCE}$, and then decreased. In order to investigate the role of passivating oxide film in the corrosive wear process, several examinations such as potentiokinetic measurement, inductively coupled plasma(ICP) spectroscopy, friction coefficient measurement, and scanning electron microscopic(SEM) measurement were carried out. From the results of such experiments, the variations of corrosive wear rate and acceleratory contribution associated with the applied potential are discussed in terms of competing effects of corrosion reaction and compositional change of passivating oxide film. In chapter IV, results on the influence of chloride ion levels on the corrosive wear rate of 304-L stainless steel in 1 N $H_2SO_4$ solution are discussed and continue fro...