cBN Sintered Binder Composition for Crack-Resistant Cutting Tools
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Solution Overview
Problem
High-cBN sintered materials used in cutting tools tend to experience sudden breakage due to weak bonding between cBN grains, leading to increased tool costs and reduced tool life, especially with the rapid increase in machine part functionality.
Innovation Solution
A cubic boron nitride sintered material with a binder comprising specific metallic elements and their compounds, including tungsten, cobalt, aluminum, titanium, zirconium, and chromium, is developed, with the second material having a thermal expansion coefficient close to cBN and a fine grain size to reduce heat cracks and improve bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content ratio of cubic boron nitride is increased to improve hardness and cutting performance, then the bonding force between grains becomes weaker, leading to sudden breakage
Solution Approach 1:
The invention uses a composite binder system comprising multiple materials (cobalt, tungsten, titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium) to achieve synergistic effects. This composite approach allows the binder to simultaneously provide strong bonding force and resistance to thermal expansion differences, resolving the contradiction between hardness and reliability in high-cBN sintered materials.
Solution Approach 2:
The invention optimizes the compositional parameters of the binder by specifying precise ranges for each metallic element and their compounds. By adjusting these parameters, the binder achieves optimal balance between bonding strength and thermal expansion compatibility with cBN grains, preventing sudden breakage while maintaining high hardness.
2Temperature
If the binder contains metallic elements with large thermal expansion differences, then thermal stress increases during cutting, causing heat cracks and reducing tool life
Solution Approach 1:
The invention specifically selects metallic elements and compounds whose thermal expansion coefficients are compatible with cubic boron nitride. By choosing materials like titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium in controlled amounts, the binder's thermal expansion matches cBN grains, minimizing thermal stress and preventing heat cracks during high-temperature cutting operations.
Solution Approach 2:
The invention controls the compositional parameters of the binder to achieve optimal thermal expansion properties. By specifying precise ranges for each metallic element and their compounds, the binder maintains thermal stability during cutting, extending tool life while withstanding high temperatures.
3Strength
If the binder grain size is large, then the binder provides sufficient bonding, but it creates stress concentration points that lead to sudden breakage
Solution Approach 1:
The invention optimizes the grain size parameter of the binder materials, specifying that they should have an average grain size of 1 μm or less. This fine-grain structure eliminates stress concentration points while maintaining sufficient bonding strength through the combined effect of multiple metallic elements and their compounds.
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 stability and longevity of cutting tools by reducing heat cracks and mechanical wear, resulting in improved cutting edge strength and wear resistance.
Implementation Method 1
the second material having a thermal expansion coefficient close to cBN and a fine grain size to reduce heat cracks
Implementation Method 2
Each of the second chemical species is a solid solution derived from at least one selected from the group consisting of nitride, carbide, and carbonitride. In each of the second chemical species, 0.1 atom % to 10 atom % of aluminum is dissolved in a solid state
Data Source
AI summary
A cubic boron nitride sintered material includes cubic boron nitride and a binder. The binder includes a first material and a second material. The first material is one or two or more first chemical species each including at least one first metallic element selected from the group consisting of tungsten, cobalt, and aluminum. Each of the first chemical species is a metal, an alloy, an intermetallic compound, a compound, or a solid solution. The second material is one or two or more second chemical species each including at least one second metallic element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium. Each of the second chemical species is a solid solution derived from at least one selected from the group consisting of nitride, carbide, and carbonitride. In each of the second chemical species, 0.1 atom % to 10 atom % of aluminum is dissolved.