Wear Resistant Tool Die Coating for Ceramic Extrusion
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Solution Overview
Problem
Tool dies used for forming green ceramic bodies experience rapid wear due to the hardness of ceramic batch materials, leading to premature failure and the need for prolonged 'break-in' periods with existing wear-resistant coatings, which impede smooth extrusion and result in green defects in the products.
Innovation Solution
A wear-resistant coating with a smooth outer surface morphology, achieved by altering the growth mechanism using dopants like boron to transition from columnar to equiaxial fine-grained structures, reducing surface roughness and increasing hardness, and comprising multiple layers with inherent porosity to tolerate strain, thereby improving the tool die's performance and extending its service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a wear resistant coating is applied to extend die service life, then the die durability is improved, but the coating requires a long pre-conditioning period before production use
Solution Approach 1:
The patent changes the surface morphology parameter of the coating by controlling grain size (fine-grained structure with mean roughness of 0.03-0.8 μm Rq) and composition (adding dopants like boron to TiCxN1-x coating), thereby reducing the pre-conditioning period while maintaining wear resistance and extending die service life
Solution Approach 2:
The patent uses composite coating materials (TiCxN1-x with boron dopant) that combine the wear resistance of refractory carbides/nitrides with the smooth surface morphology characteristic of metals, eliminating the need for long pre-conditioning while providing extended die life
2Reliability
If a wear resistant coating with high hardness is used, then the coating resistance to wear is improved, but the surface roughness increases causing extrusion defects
Solution Approach 1:
The patent changes the grain size parameter to fine-grained structure (mean roughness 0.03-0.8 μm Rq) while maintaining high hardness through dopant addition, thereby achieving both wear resistance and smooth surface finish that prevents extrusion defects
Solution Approach 2:
The patent creates different properties at different scales: coarse underlying structure for wear resistance and hardness, with a fine-grained outer surface layer (0.03-0.8 μm Rq) for smooth extrusion, applying local quality differentiation to satisfy conflicting requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified coating significantly reduces surface roughness, decreases extrusion pressure, stabilizes the hardware setup, and extends the tool die's service life by enhancing the smooth flow of ceramic materials and reducing defects in the extruded products.
Implementation Method 1
Such coatings are sometimes fabricated from refractory materials such as inorganic carbides, nitrides, and combinations thereof using chemical vapor deposition
Data Source
AI summary
A tool die for forming a green ceramic body. The tool die has a wear resistant coating that is deposited on a substrate and has an outer or free surface having a morphology that provides a mean roughness in a range from about 0.03 μm up to about 0.8 μm Rq. In one embodiment, the wear resistant coating has multiple alternating layers of fine grained and coarse grained materials. Methods of making the tool die and wear resistant coating are also provided.