cBN Coated Cutting Tool With Direct Nitride Coating Adhesion
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Solution Overview
Problem
Existing coated cutting tools with cubic boron nitride (cBN)-based substrates suffer from reduced toughness, wear resistance, and adhesion issues due to impurities in the binder phase, which also affect the tool life and surface quality.
Innovation Solution
A coated cutting tool is developed with a substrate comprising cBN and a binder phase with controlled impurity levels, specifically optimized to reduce aluminium and tungsten impurities, and a nitride coating deposited directly onto the substrate without interlayers, using high power impulse magnetron sputtering (HIPIMS) for improved adhesion and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sintering process with high pressure and temperature is used to produce cBN-based substrates, then the substrate can be formed with binder phase, but impurities such as W compounds, TiB2 and α-alumina are formed which reduce toughness and wear resistance
Solution Approach 1:
The patent removes harmful impurities (W compounds, TiB2, α-alumina) from the binder phase by extracting them during the sintering process through controlled atmosphere and temperature parameters, thereby improving toughness and wear resistance while maintaining the necessary binder phase structure
Solution Approach 2:
The patent changes sintering parameters (temperature, pressure, atmosphere composition, holding time) to optimize the formation of binder phase while minimizing impurity generation, specifically controlling the oxidation atmosphere to prevent α-alumina formation and adjusting temperature to avoid excessive TiB2 formation
2Manufacturing precision
If conventional grinding is used to produce cBN-based substrates, then the substrate shape can be formed, but the surface is impaired which results in reduced adhesion of deposited coating
Solution Approach 1:
The patent applies preliminary surface treatment (chemical etching or plasma treatment) before coating deposition to restore and enhance the substrate surface quality, removing grinding-induced damage and creating a surface with improved mechanical properties and higher coating adhesion capability
Solution Approach 2:
The patent changes surface parameters (roughness, chemical composition, surface energy) through controlled etching or plasma treatment to optimize coating adhesion while maintaining the overall substrate geometry and manufacturing precision
3Device complexity
If PVD coating is deposited directly on substrate without interlayers, then the coating structure is simple, but the adhesion is not satisfactory resulting in limited life span
Solution Approach 1:
The patent changes the substrate surface parameters (roughness, chemical composition, surface energy) through preliminary treatment to enable direct coating deposition with high adhesion, eliminating the need for interlayers while extending tool life span through improved coating-substrate bonding
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 solution significantly enhances the adhesion of the coating to the substrate, leading to improved wear resistance, extended tool life, and reduced diffusion of workpiece material into the coating, thereby addressing the limitations of existing technologies.
Implementation Method 1
using high power impulse magnetron sputtering (HIPIMS) for improved adhesion and wear resistance
Data Source
AI summary
A coated cutting tool includes a substrate including cubic boron nitride and a binder phase including TiCyN1-y, wherein 0≤y≤1. The binder phase contains impurities of aluminium expressed as a net intensity ratio of Al to Ti, and/or tungsten expressed as a net intensity ratio of W to Ti, and/or TiB2 expressed as a ratio of the net peak height of the TiB2 peak to the net peak height of the TiCN peak, and/or α-alumina expressed as a ratio of the net peak height of the α-alumina peak to the net peak height of the TiCN peak. A coating is deposited on the substrate and includes at least one nitride composed of a nitride of one or more elements belonging to group 4-6 of the periodic table of elements, or a nitride of Al and/or Si together with one or more elements belonging to group 4-6.