Spark Plug Electrode Joint Structure for Thermal Stress Relief

The patent applies parameter changes by transitioning from traditional laser welding to additive manufacturing processes (such as selective laser melting or electron beam melting) with modified process parameters. The additive manufacturing approach uses controlled layer-by-layer deposition and melting parameters that reduce thermal gradients and residual stresses, thereby preventing cracking while maintaining joint strength between the precious metal electrode tip and nickel alloy electrode body.

The patent employs composite materials by creating a gradient structure in the joint region where the composition transitions from pure precious metal at the tip to nickel alloy in the body, with intermediate layers containing mixed compositions. This composite approach allows the joint to accommodate differential thermal expansion between the two base materials, reducing thermal stresses and preventing cracking during operation.

The patent applies local quality by concentrating precious metals specifically in the electrode tip region where they are most needed for erosion and corrosion resistance during sparking. The electrode body is made from more cost-effective nickel alloy materials, while the precious metal coating or deposition is applied locally to the tip surface, optimizing performance while minimizing precious metal consumption and cost.

The patent segments the electrode into distinct functional zones: the electrode body made from nickel alloy and the electrode tip made from or coated with precious metals. This segmentation allows each part to be optimized for its specific function - the body for structural support and electrical conduction, and the tip for spark generation and resistance to erosion/corrosion - while using precious metals only where necessary.