Cermet Cutting Tool with Composite Hard Phase for Defect Resistance
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Solution Overview
Problem
Cermets used in cutting tools and wear-resistant members have insufficient defect resistance despite providing wear resistance, necessitating a composition that enhances both properties.
Innovation Solution
A cermet composition featuring a bonding phase with Co or Ni, hard phases of TiCN and composite carbonitrides with specific particle diameters and W content, and an aggregate part formed by interlinking these phases, manufactured through a controlled baking process to achieve improved defect resistance without compromising wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cermet composition with Ti-based hard phase and Co/Ni bonding phase is used, then wear resistance is improved, but defect resistance remains insufficient
Solution Approach 1:
The patent employs a composite hard phase structure combining TiCN with composite carbonitrides containing Group IV-V-VI metals. This multi-phase composite approach creates a synergistic effect where the TiCN provides wear resistance while the composite carbonitride phases with controlled W content distribution enhance defect resistance through crack deflection mechanisms, resolving the contradiction between wear resistance and defect resistance
Solution Approach 2:
The patent implements local quality by creating an aggregate part where W content is non-uniformly distributed - with maximum W content in the inner part being more than 1.1 times the average W content in the outer circumferential part. This localized concentration of W in specific regions enhances defect resistance at critical locations while maintaining overall wear resistance of the cermet
2Reliability
If hard phase particle size is increased to improve toughness, then defect resistance improves, but wear resistance decreases
Solution Approach 1:
The patent segments the hard phase into two distinct size categories: first hard phase (TiCN) with average particle diameter of 0.05-1 μm for wear resistance, and second hard phase (composite carbonitride) with average particle diameter of 0.2-2 μm for defect resistance. This segmentation allows each phase to optimize its particle size for its specific function, resolving the trade-off between wear resistance and defect resistance
Solution Approach 2:
The patent changes the particle diameter parameter of the hard phase from a single size to a bimodal distribution with two distinct ranges. The first hard phase uses smaller particles (0.05-1 μm) to maintain wear resistance, while the second hard phase uses larger particles (0.2-2 μm) to improve defect resistance through crack deflection, achieving both objectives simultaneously
3Reliability
If aggregate part proportion is increased to improve defect resistance, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a concrete parameter range for the aggregate part proportion (20-60% of total hard phase area), which simplifies manufacturing by providing clear control targets. Within this range, the non-uniform W content distribution is achieved through controlled mixing and sintering processes, balancing defect resistance improvement with manufacturing feasibility
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 cermet exhibits enhanced wear resistance and defect resistance, enabling long-term cutting tool performance by maintaining high wear resistance and improving toughness through crack deflection and energy weakening mechanisms.
Implementation Method 1
a baking step (c) in one of the vacuum and an inert gas atmosphere at from 30 Pa to 2000 Pa, raising the temperature from the baking temperature T1 to a baking temperature T2 of from 1500° C. to 1600° C.
Data Source
AI summary
A cermet (1) includes a bonding phase (2) and a hard phase (4). The hard phase (4) includes: a first hard phase (5) composed of TiCN; and a second hard phase (6) composed of a composite carbonitride of Ti, which is greater than the average particle diameter of the first hard phase (5). The cermet (1) further includes an aggregate part (10) formed by interlinking parts of the second hard phase (6). The second hard phase (6) forming the aggregate part (10) includes a 2a-th hard phase (7) having a maximum W content of an inner part thereof that is more than 1.1 times as great as an average W content of an outer circumferential part thereof, in terms of mass ratio. The aggregate part (10) composes a proportion of from 20% to 60% of the cermet (1) in terms of surface area.