WC-W Super-Hard Sintered Material Without W2C Formation
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Solution Overview
Problem
Sintered materials containing tungsten (W) and tungsten carbide (WC) face challenges with the generation of low-strength WC (W2C) at high temperatures, leading to reduced hardness and strength, especially when used in severe conditions or high-temperature applications.
Innovation Solution
A super-hard sintered material is developed using nano-sized W and WC powders with adjusted grain sizes and sintering conditions at 1450°C or less to prevent W2C formation, employing a hydrogen reduction method and hot press or spark plasma sintering techniques to achieve high hardness and strength without generating W2C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sintering is performed at high temperature (1750-1900°C) to obtain cemented carbide with W binder phase, then the material can be formed with WC and W, but W transforms into W2C which has low hardness and low strength
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (1750-1900°C) to a lower range (1400-1650°C), which prevents W transformation into W2C while still achieving complete sintering. This parameter change resolves the contradiction by finding an optimal temperature window that maintains both formability and mechanical properties.
Solution Approach 2:
The patent performs preliminary classification of WC particles to create a specific particle size distribution before sintering. This preliminary action ensures proper packing and sintering behavior at the lower temperature, preventing W2C formation while achieving dense microstructure and high strength.
2Stability of the object's composition
If sintering temperature is increased to improve densification, then compactness improves, but W transforms into W2C which reduces hardness
Solution Approach 1:
The patent identifies and applies an optimal sintering temperature range (1400-1650°C) that achieves complete densification and compactness without causing W transformation into W2C. This parameter optimization resolves the contradiction by finding the temperature window where both compactness and hardness are maximized.
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 resulting material exhibits excellent high hardness, strength, compactness, and corrosion resistance, suitable for cutting tools and high-temperature applications, with no detectable W2C by X-ray diffraction, extending tool life and maintaining hardness across varying temperatures.
Implementation Method 1
a sintered material in which WC (tungsten carbide) particles known as a high hardness, high strength and high melting point ceramic are set as a hard phase, and tungsten metal (W) having high affinity with WC and high strength and high melting point like WC is set as a binder phase
Implementation Method 2
employing a hydrogen reduction method and hot press or spark plasma sintering techniques
Data Source
Figure 1
Figure 2~3
AI summary
Provided is a super-hard sintered material which contains 5 to 55 mass% of W and a WC balance containing inevitable impurities and is excellent in high hardness and high strength.