Formation of Fe-TiC composite clad layers on steel using the combustion synthesis process

• Published in: Surface & coatings technology 2018-08, Vol.347, p.217-224
• Main Authors: Rahimi-Vahedi, Abtin, Adeli, Mandana, Saghafian, Hassan
• Format: Article
• Language: English
• Subjects: Adhesion; Ceramics; Chemical composition; Chemical precipitation; Chemical synthesis; Clad; Cold pressing; Combustion synthesis; Exothermic reactions; Fe-Ti-C composite; Heat sinks; Heating; Mechanism; Microstructure; Organic chemistry; Sintering (powder metallurgy); Steel; Substrates; Titanium carbide
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.04.086

The application of thermal explosion mode of the combustion synthesis process to form Fe-TiC composite layers on a steel substrate was investigated. Starting powder mixtures of Fe, Ti, and C with different percentages of iron were cold-pressed onto a steel hollow disk and exposed to high heating rates under an argon atmosphere. A self-sustaining, exothermic reaction took place in all samples. In samples with lower Fe amounts (higher amount of Ti + C) poor clad/interface adhesion was obtained due to too intensive reactions and high amount of interfacial pores, while clad layers with higher Fe contents demonstrated increasingly better adhesion as revealed by SEM analysis. Microstructural studies on samples with lower Fe amounts showed very fine, granular TiC particles which were dispersed in a Fe-rich matrix following a dissolution-precipitation mechanism. Samples with higher amounts of Fe showed partial reaction on Ti particles, resulting in a distribution of hard particles consisting of distinct layers with differing chemical compositions. Since the released reaction heat is mostly consumed for heating-up and sintering of iron particles, Fe particles act as heat sinks giving rise to a deficiency of exothermic heat for the completion of reaction. Even in case of incomplete reactions, the distribution of hard particles throughout the softer iron matrix can improve the overall hardness of the clad layer. •Combustion synthesis was used to form Fe-based composite clad layers on steel.•Clad layers with good adherence to the substrate were formed.•Higher amounts of Fe in the reacting powder mixture resulted in better adhesion.•A mechanism was proposed for the formation of Fe-Ti-C clad layers.