What is a Three-Way Catalytic Converter in a Car?
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The three-way catalytic converter is the most important external purification device installed in a car's exhaust system. It converts harmful gases such as CO, HC, and NOx emitted from the vehicle's exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Modern cars are all equipped with three-way catalytic converters. Only vehicles produced in earlier years that did not meet the China II emission standards lacked this component. Composition of a Three-Way Catalytic Converter: A three-way catalytic converter generally consists of four parts: the shell, vibration damping layer, substrate, and catalyst coating. The shell is made of stainless steel to prevent oxide scale from peeling off, which could clog the substrate. The vibration damping layer is composed of gaskets or wire mesh pads, serving to seal, insulate, and secure the substrate. To protect the substrate from damage caused by vibration, thermal deformation, and other factors, the gaskets are made of expanded mica and aluminum silicate fibers, bonded together with adhesive. The substrate is constructed from honeycomb-shaped ceramic materials, though many also use metal (including stainless steel) materials. The catalyst consists of precious metals such as platinum, rhodium, and palladium, which are sprayed onto the substrate to form the purifying agent.
