Chromium-Gradient Carbide Mining Insert for Wear-Resistant Surfaces
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Solution Overview
Problem
Cemented carbide mining inserts face challenges in achieving a balance between toughness and wear resistance, with existing methods not fully optimizing the material properties for extended lifespan and improved performance in rock drilling and mineral cutting applications.
Innovation Solution
A method involving a green mining insert compact formed from a WC-based hard phase and binder, with a second powder containing a grain refiner compound and carbon-based grain growth promoter applied to the surface, sintered at 1300°C to 1600°C to create a chemical and hardness gradient, optimizing the Cr/binder mass ratio for enhanced wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a higher binder content is used to increase toughness, then the toughness of the cemented carbide is improved, but the hardness and wear resistance decrease
Solution Approach 1:
The patent applies different binder contents to different regions of the mining insert. The bulk material contains a higher binder content (e.g., 6-12 wt% Co) to provide toughness and resistance to catastrophic failure, while the surface layer contains a lower binder content (e.g., 2-6 wt% Co) to provide high hardness and wear resistance. This spatial variation in material composition resolves the contradiction by allowing each region to optimize for its specific functional requirements.
Solution Approach 2:
The mining insert is divided into distinct zones with different material properties: a bulk zone and a surface zone. This segmentation allows independent optimization of toughness in the bulk and wear resistance in the surface layer, eliminating the need to choose a single binder content that compromises either property.
2Reliability
If a finer hard phase grain size is used to increase hardness and wear resistance, then the hardness is improved, but the impact resistance decreases
Solution Approach 1:
The patent employs different hard phase grain sizes in different regions. The bulk material contains coarser grains (e.g., 2-5 μm) that provide impact resistance, while the surface layer contains finer grains (e.g., 0.5-2 μm) that deliver high hardness and wear resistance. This local differentiation resolves the contradiction between grain size and its opposing effects on toughness versus wear resistance.
3Ease of manufacture
If a uniform material composition is used throughout the insert, then the manufacturing process is simplified, but the operative performance and lifespan are limited
Solution Approach 1:
The manufacturing process is segmented into two main stages: forming the bulk material with optimal toughness properties, then applying a surface layer with optimal wear resistance properties. While more complex than uniform composition, this segmented approach maintains relative manufacturing simplicity while dramatically extending insert lifespan by addressing both toughness and wear resistance in their respective zones.
4Reliability
If the surface layer is made harder to improve wear resistance, then the wear resistance is improved, but the toughness of the surface layer decreases
Solution Approach 1:
The surface layer is designed with lower binder content and finer grains to achieve high hardness and wear resistance. The bulk material provides the toughness that the surface layer sacrifices. This local quality differentiation allows the surface to be optimized for wear resistance without requiring the entire insert to compromise toughness, as the bulk material compensates for the surface layer's reduced toughness.
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 method produces cemented carbide mining inserts with improved wear properties and extended lifespan by creating a chemical and hardness gradient, enhancing wear resistance and corrosion resistance through the controlled distribution of chromium and binder phases.
Implementation Method 1
sintering the green mining insert compact to produce a cemented carbide mining insert
Implementation Method 2
applying a second powder comprising a grain refiner compound and / or a carbon based grain growth promoter to at least one portion of the surface of the green mining insert compact
Implementation Method 3
at least one part of an upper surface zone has on average a larger average WC grain size than the intermediate surface zone
Implementation Method 4
the grain refiner compound in the second powder comprises Cr and C and/or N
Data Source
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AI summary
The present disclosure relates method of making a cemented carbide mining insert, a cemented carbide mining insert with having a chemical and hardness gradient and to the use thereof wherein the cemented carbide mining insert comprises Cr.