Homogeneous Complex Carbonitride Powder for Hard Alloy Strength
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Solution Overview
Problem
Existing cermets and hard alloys face challenges in achieving high strength due to non-uniform composition in their hard phases, leading to difficulties in increasing both hardness and fracture toughness.
Innovation Solution
A complex carbonitride powder with a homogeneous composition, primarily containing titanium and additional elements like zirconium, hafnium, or tungsten, is produced through a method involving mixing oxide powders, granulation, and heat treatment at high temperatures in a nitrogen atmosphere, resulting in particles with uniform composition and enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mixing methods are used to prepare hard phase powders, then production process is simple, but composition uniformity is poor leading to non-homogeneous hard phases
Solution Approach 1:
The invention applies preliminary action by performing granulation of the mixed powder before heat treatment. This preliminary granulation step creates uniform green granules that ensure homogeneous composition distribution in the final hard phase, resolving the contradiction between composition uniformity and process simplicity.
Solution Approach 2:
The invention changes the physical state and morphology parameters of the mixed powder through granulation, transforming fine powders into granules with controlled size distribution (0.1-5mm). This parameter change maintains composition uniformity while managing production complexity through standardized granulation processes.
2Strength
If high temperature heat treatment is applied to form complex carbonitride, then hard phase formation is achieved, but composition non-uniformity persists and active elements are lost
Solution Approach 1:
The granulation step performed before heat treatment serves as a preliminary action that pre-establishes uniform composition distribution. This prevents composition non-uniformity during the subsequent high-temperature heat treatment, while the granulated structure also helps retain active elements like Ti and W by reducing oxidation surface area.
Solution Approach 2:
The invention uses a nitrogen atmosphere during heat treatment at 1800-2200°C to create an inert environment that prevents oxidation of active elements (Ti, W) while allowing formation of complex carbonitride. This resolves the contradiction by maintaining composition uniformity and element retention during the strength-enhancing heat treatment.
3Strength
If core structure with different composition regions is formed, then traditional hard alloy structure is achieved, but both hardness and fracture toughness cannot be increased simultaneously
Solution Approach 1:
The invention applies homogeneity by ensuring uniform distribution of Ti and additional elements (W, Mo, Nb, Ta) throughout the complex carbonitride phase. The homogeneous composition (with additional elements at 5-30 atom%) creates a uniform microstructure that simultaneously enhances both hardness and fracture toughness, resolving the traditional trade-off between these properties.
4Manufacturing precision
If oxide powders are mixed without granulation, then production steps are fewer, but composition homogeneity cannot be achieved in final product
Solution Approach 1:
Granulation is performed as a preliminary action before heat treatment, creating uniform green granules that ensure homogeneous composition. This preliminary step, while adding a process stage, actually improves production efficiency by preventing composition defects that would require rework, and by enabling continuous production workflows.
Solution Approach 2:
The granulation process changes the physical parameters of the mixed powder (particle size, morphology, density) to create granules with optimal characteristics for subsequent heat treatment. This parameter optimization achieves composition homogeneity while maintaining production efficiency through standardized granulation parameters.
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 a hard alloy with homogeneous complex carbonitride phases, significantly improving both hardness and fracture toughness by ensuring uniform composition and retention of active elements during the heat treatment process.
Implementation Method 1
a heat treatment step of subjecting the granules to a heat treatment at a temperature of greater than or equal to 1800° C. in a nitrogen-gas-containing nitrogen atmosphere gas to form a complex carbonitride powder
Implementation Method 2
subjecting the granules to a heat treatment at a temperature of greater than or equal to 1800° C. in a nitrogen-gas-containing nitrogen atmosphere gas to form a complex carbonitride powder
Data Source
AI summary
A complex carbonitride powder contains Ti as a main component element and at least one additional element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, and Si. The complex carbonitride powder includes a plurality of complex carbonitride particles containing Ti and the additional element. The plurality of complex carbonitride particles include a plurality of homogeneous composition particles where average concentrations of Ti and the additional element in each complex carbonitride particle have a difference in a range of greater than or equal to −5 atom % and less than or equal to 5 atom % from average concentrations of Ti and the additional element in the whole complex carbonitride powder. A cross-sectional area of the homogeneous composition particles is greater than or equal to 90% of a cross-sectional area of the complex carbonitride particles 1p.