Evaluation of the Corrosion Resistance of Phosphate Coatings Deposited on the Surface of the Carbon Steel Used for Carabiners Manufacturing

Diana-Petronela Burduhos-Nergis,Costica Bejinariu,Petrica Vizureanu,Andrei Victor Sandu

doi:10.3390/app10082753

Abstract

This study aims to evaluate the corrosion resistance of carbon steel, used for carabiners manufacturing, coated with three different types of phosphate layer. The phosphate layers have been obtained by phosphate conversion coating with three different types of phosphate solutions: zinc-based solution, zinc-iron-based phosphate solution, and manganese-based phosphate solution. Additionally, the test was performed on zinc phosphate samples impregnated with molybdenum bisulfate-based oil and zinc phosphate samples further coated with a layer of elastomer-based paint. Considering the areas where the carabiners are used (civil engineering, navigation, oil industry, rescue operations, etc.), the corrosive environments studied are rainwater, Black Sea water, and fire extinguishing solution. The structure of the deposited layers was studied by scanning electron microscopy, while the interface structure between the alloy and corrosive environment was analyzed by electrochemical impedance spectroscopy. According to this study, the corrosion resistance of zinc-based phosphate coated samples and zinc/iron-based phosphate coated samples is higher than that of the studied carbon steel samples, despite the corrosion environment. Also, the most aggressive corrosion environment was the fire extinguishing solution.

Highlights

At the beginning of the 20th century, for safety reasons during climbing, the first safety rings were invented, previously in 1910, Hans Fiechtl invented and manufactured the python [1]
The phosphate crystals present on the steel surface are fine, compact, and have the form of flowers or plates, this form being specific to the hopeite
The main difference between I-Zn and II-Zn/Fe samples is the size of the phosphate crystal, which is much smaller in the case of the II-Zn/Fe samples

Summary

Introduction

At the beginning of the 20th century, for safety reasons during climbing, the first safety rings were invented, previously in 1910, Hans Fiechtl invented and manufactured the python [1]. The geographical extension of mountaineering was an important factor in the modernization of height protection. In this regard, the python becomes a mandatory accessory even though it was difficult to use, this problem has been solved when carabiners were invented [2]. The most used materials from which the carabiners are made are aluminum and steel. Aluminum carabiners are used in places where weight is important (e.g., mountain climbing), while steel carabiners

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