Researches of cast iron piston rings strengthened by laser

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In order to decrease wear losses between piston rings and cylinder liners and improve the partner adaptability, laser cladding and electroplating techniques were adopted to form coatings on the surfaces of piston rings made of nodular cast iron. Fe-based composite layers reinforced by in situ particles were formed by laser cladding using preplaced FeCSiB alloy powders on nodular cast iron matrix. The chromium-plated layers were formed on the nodular cast iron matrix. By simulating the operating conditions of piston rings and cylinder liners in the diesel engine, the Optimal SRV tests were carried out using laser cladding and chromium-plated strengthening piston rings as upper samples and segments of grey cast iron cylinder liners as lower samples. The morphologies of worn scars were observed with optical microscopy and scanning electron microscopy (SEM). The SRV tests show that laser cladding processes reduce the wear depth of both the piston rings and the partner cylinder liners，have the lower friction coefficient (0.067∼0.085), which reduces with the increase of wear time. It can be concluded that the piston rings processed by laser strengthening have good wear resistance and extensive partner adaptability and the mechanism is slightly scratching. The results demonstrate that the friction coefficient (0.1170～0.1332) between the chromium-plated rings and cast iron cylinder liners increased with the increase of wear time in the same conditions and the wear mechanism is severe adhesive wear.In order to decrease wear losses between piston rings and cylinder liners and improve the partner adaptability, laser cladding and electroplating techniques were adopted to form coatings on the surfaces of piston rings made of nodular cast iron. Fe-based composite layers reinforced by in situ particles were formed by laser cladding using preplaced FeCSiB alloy powders on nodular cast iron matrix. The chromium-plated layers were formed on the nodular cast iron matrix. By simulating the operating conditions of piston rings and cylinder liners in the diesel engine, the Optimal SRV tests were carried out using laser cladding and chromium-plated strengthening piston rings as upper samples and segments of grey cast iron cylinder liners as lower samples. The morphologies of worn scars were observed with optical microscopy and scanning electron microscopy (SEM). The SRV tests show that laser cladding processes reduce the wear depth of both the piston rings and the partner cylinder liners，have the lower friction c...