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Corrosion of fasteners in concrete: Literature review and discussion of current test methods
Published in Alphose Zingoni, Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, 2022
Electroplating is the most used method for fastener coating deposition. Hot-dip galvanizing is a typical process to deposit zinc coatings by immerging the fasteners into a bath of molten zinc. Mechanical plating is a process in which metallic coatings are deposited onto small metallic parts, such as fasteners, using kinetic energy at room temperature. Zinc flake coating is a non-electrolytically applied metallic coating. Sherardizing coatings consist of Zn-Fe alloy layers obtained by sherardizing. Finally, there are nonmetallic coatings which are generally categorized into two groups: (i) organic, e.g. paints; (ii) inorganic, e.g. phosphates.
An Experimental Study on Factors Affecting the Friction Coefficients in Electroplated Bolts
Published in Tribology Transactions, 2020
The single largest fastener consumer is the automotive industry, accounting for approximately 42% of the fastener industry (1). Bolts are the main type of automotive fasteners. Typically, bolts for the automotive industry are coated to provide corrosion resistance and to modify the torque–tension relationship, as well as to improve other properties like appearance, wear resistance, heat resistance, fluid compatibility, and so on. There are various methods for coating bolts, such as electroplating (electro-galvanizing), zinc flake coating, hot-dip galvanizing, mechanical plating, and electrocoating. Among these methods, electroplating and zinc flake coating are widely used for fasteners in the automotive industry. Although these two technologies are fundamentally different, electrolytically or nonelectrolytically applied, both technologies are based on the sacrificial properties of zinc against steel and can be used for similar applications. Generally, for zinc flake coating there is no risk of hydrogen embrittlement and the corrosion resistance is better than that of zinc electrodeposits, whereas electroplating more easily achieves a relatively homogenous coating thickness on complex-shaped parts and superior corrosion resistance can be achieved by Zn-Ni alloy electrodeposits. The present study will focus on electroplated bolts.