The Cathodic Electrolytic Plasma Hardening of Steel and Cast Iron Based Automotive Camshafts

<p dir="ltr">This study investigates the application of cathodic electrolytic plasma hardening (CEPH) for enhancing the surface hardness and wear resistance of camshaft lobes made from various cast iron and steel grades. CEPH, a novel thermochemical surface modification process, was employed using a specially designed ceramic ellipse-shaped plasma nozzle to optimize heating and electrolyte flow on complex geometries like camshaft lobes. The camshafts were mounted on a CNC lathe for horizontal rotation during processing in an aqueous carbonate electrolyte. The external surfaces of the lobes were heated and quenched, achieving surface hardness values of 50–60 HRc with no observed distortion. Hardness depths ranged from 0.1 mm to 5 mm across different lobes. The CEPH process produced a homogeneous martensitic microstructure with multi-phase mixtures (Fe₂₃O₄, austenite, martensite, (Fe)ₓC, and nanocrystalline layers), offering superior wear resistance compared to traditional methods like flame and induction hardening. Unlike these methods, CEPH avoids distortion and the need for precise coil coupling, making it suitable for localized hardening of automotive components like camshafts. This pilot-scale study is the first to directly address CEPH hardening of camshafts, demonstrating its potential for industrial applications requiring high wear resistance and durability.</p>