Fretting corrosion of lubricated tin‐plated contacts

Abstract

PurposeThe objective of this paper is to study the effect of a commercial lubricant, which contains a 50‐50 mixture of zinc diamyldithiocarbamate and petroleum oil, on the fretting corrosion of tin‐plated copper alloy contacts.Design/methodology/approachThe change in contact resistance as a function of fretting cycles was used to assess the effectiveness of the lubricant in preventing the fretting corrosion of tin‐plated contacts. The surface profile, surface roughness, extent of fretting damage and extent of oxidation of the contact zone were assessed by a laser scanning microscope and surface analytical techniques to correlate the change in contact resistance with fretting cycles.FindingsThe lubricant film provides a surface coverage of 6.76±1 mg/cm2 and it easily establishes metallic asperity contact between the mated tin‐plated contacts. The contact resistance of lubricated contacts remains stable for several thousand fretting cycles. Lubricated contacts reach a threshold value of 0.1 Ω around 100,000 cycles, whereas unlubricated contact reaches this value around 13,500 cycles itself. For lubricated contacts, the extent of mechanical wear of the tin coating is significantly reduced. As a result, they experience a lesser damage at the contact zone and exhibit a smoother profile. The formation of tin oxide is not appreciable and there is no oxide accumulation at the contact zone even at 380,000 cycles. The lubricant is very effective in delaying the fretting wear during the initial stages and in preventing the oxidation and accumulation of oxidation products at the contact zone in the later stages.Originality/valueMetallic dialkyldithiocarbamates are useful anti‐wear and extreme pressure additives for lubricating oils. Dithiocarbamates improve the antioxidant properties of the lubricants and are effective in reducing the wear and increasing the friction‐reducing and load‐carrying ability of the base stock. The use of molybdenum dithiocarbamate as a grease additive is found to be effective in reducing fretting corrosion of ball bearings under random rotary vibrating conditions. The effect of dithiocarbamate containing lubricant oils or greases on the fretting corrosion of electrical contacts has not far been studied. The paper explores the effect of a lubricant that contains a 50‐50 mixture of petroleum oil and zinc diamyldithiocarbamate on the fretting corrosion of tin‐plated contact.

Determination of fretting parameters of hoisting rope in coalmine and fretting-fatigue behavior of steel wires

“…a perfect hysteresis loop of the rectangular shape, which results in the rapid elimination of the pollution film at the contact surface. As the fretting cycles increase, the maximum tangential force increases due to the increased number and size of fretting scars as well as the surface plastic deformation of local zones (Zhou and Vincent, 1995;Sankara Narayanan et al, 2008). However, the area inside the hysteresis loop and relative slip range decrease significantly, which clearly indicates that the partial slip condition develops with a less opened hysteresis loop.…”

Analysis of surface roughness morphology with TRIZ methodology in automotive electrical contacts: Design against third body fretting-corrosion

“…This group also performed unique in situ measurements of temperature, humidity and pressure in automotive connectors, which provided a better understanding of the actual operating conditions of these components [14]. In recent years, a research group at Yonsei University in South Korea has been very active in this field, publishing a dozen articles on tinned contacts covering charging conditions, wear analysis, lubricants, current charging, contact temperature and numerical methods [15][16][17][18][19][20][21][22][23][24][25][26].…”