TiN-Based Sintered Cutting Tool Composition for Wear and Toughness
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Solution Overview
Problem
Cutting tools face challenges in achieving a balance between toughness and wear resistance, with WC-based cemented carbides being costly due to rare metal usage and TiCN-based cermets being prone to chipping and fracturing, leading to short tool service lives.
Innovation Solution
A TiN-based sintered body with a specific composition of 70-94% TiN phase, 1-25% Mo2C phase, and a binder phase containing Fe and Ni, optimized to enhance wettability and sinterability, preventing the formation of detrimental heterophases, resulting in a cutting tool with improved toughness and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If TiC-based sintered body is used for cutting tool, then wear resistance is improved, but toughness deteriorates and thermal shock resistance worsens
Solution Approach 1:
The patent uses a composite material system consisting of TiN hard phase, Mo2C dispersoid phase, and Fe-Ni binder phase. This composite structure combines the wear resistance of TiN with the toughness contribution from the Fe-Ni binder and Mo2C particles, resolving the contradiction between wear resistance and toughness that plagues TiC-based materials.
Solution Approach 2:
The patent changes the chemical composition parameters by using TiN instead of TiC as the hard phase, and optimizes the binder phase composition to Fe-Ni with specific ratios. It also controls the oxygen content to 0.15% or less and adjusts grain size distribution, thereby improving both toughness and wear resistance simultaneously.
2Strength
If TiCN-based cermet is used for cutting tool, then wear resistance and finish surface roughness are improved, but toughness deteriorates
Solution Approach 1:
The patent extracts the problematic TiCN hard phase and replaces it with TiN hard phase combined with Mo2C dispersoid. This extraction of the problematic component (TiCN) while retaining the beneficial properties (wear resistance) allows improvement in toughness without sacrificing wear resistance or surface finish quality.
Solution Approach 2:
The patent changes the hard phase composition from TiCN to TiN-based system with controlled oxygen content (≤0.15%). This parameter change in chemical composition fundamentally alters the material properties, achieving both high wear resistance and improved toughness compared to conventional TiCN cermets.
3Strength
If WC-based cemented carbide is used for cutting tool, then toughness is improved, but wear resistance deteriorates and cost increases due to rare metal usage
Solution Approach 1:
The patent replaces expensive rare metals (W and Co) with cheaper abundant metals (Ti, Fe, Ni, Mo). The TiN-based sintered body achieves comparable or superior performance at lower cost, effectively substituting expensive materials with more economical alternatives without sacrificing tool life or performance.
Solution Approach 2:
The patent creates a composite material system using TiN hard phase, Mo2C dispersoid, and Fe-Ni binder phase. This composite structure provides both the toughness needed to replace WC-Co and the wear resistance required to match or exceed TiCN-based cermets, eliminating the need for rare metals while maintaining performance.
4Strength
If Fe-based binder phase is used in TiN sintered body, then toughness is improved, but hardness deteriorates due to bcc structure formation
Solution Approach 1:
The patent changes the crystal structure parameter of the binder phase from bcc to fcc by optimizing the Fe-Ni composition ratio and controlling sintering conditions. This parameter change in crystal structure transforms the binder phase properties, achieving both high toughness and high hardness simultaneously, which is not possible with conventional Fe-based binders.
Solution Approach 2:
The patent creates local quality differentiation by forming Mo2C dispersoid particles within the Fe-Ni binder phase. The Mo2C particles provide local hardening effects while the Fe-Ni fcc binder provides toughness, creating a microstructure with spatially varying properties that achieves overall high hardness and 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 TiN-based cutting tool exhibits excellent wear resistance and abnormal damage resistance, comparable to WC-based cemented carbides and TiCN-based cermets, ensuring extended tool service life and cost-effective production without rare metals.
Implementation Method 1
a sintered structure containing 70 to 94 area % of a TiN phase, and 1 to 25 area % of a Mo2C phase, and a remainder including a binder phase
Data Source
AI summary
Disclosed is a TiN-based sintered body and a cutting tool made of the TiN-based sintered body, which has 70 to 94 area % of a TiN phase, 1 to 25 area % of a Mo2C phase, and a remainder including a binder phase. The binder phase contains Fe and Ni whose total area ratio is 5 to 15 area %, and an amount of Ni to a total amount of Fe and Ni is 15 to 35 mass %. When an X-ray diffraction profile is measured in the cross section of the TiN-based sintered body, the diffraction peaks of TiN, Mo2C and Fe—Ni having an fcc structure are present, but the diffraction peaks of Fe—Ni having a bcc structure, a Fe3Mo3C phase, and a Fe3Mo3N phase are absent. The lattice constant of the TiN is 4.235 to 4.245 Å, and that of the Fe—Ni having an fcc structure is 3.58 to 3.62 Å.