ZrN Binder Phase for cBN Cutting Tool Wear Resistance
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Solution Overview
Problem
Current cutting tools for hard steel machining at high speeds suffer from rapid wear due to frictional heat and reduced fracture toughness, leading to premature failure in continuous and interrupted cutting.
Innovation Solution
Incorporating 30 to 80 vol.% cubic boron nitride with a binder phase containing 2 to 10 vol.% ZrN, and optimizing powder blending methods like attritor milling and spray drying to enhance homogeneity, results in improved wear resistance and toughness without sacrificing performance in interrupted cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat resistant ceramic such as TiN is added to improve wear resistance at high speeds, then wear resistance is improved, but fracture toughness is reduced
Solution Approach 1:
The patent changes the chemical composition parameter of the binder phase by replacing traditional TiN-based ceramics with ZrN (zirconium nitride). This substitution maintains the heat resistant properties needed for wear resistance while ZrN's specific crystal structure and bonding characteristics provide improved fracture toughness, thus resolving the contradiction between wear resistance and fracture toughness at high cutting speeds
Solution Approach 2:
The patent creates a composite sintered compact consisting of cubic boron nitride (cBN) particles combined with a binder phase containing ZrN. This composite structure allows the cBN to provide extreme hardness and wear resistance while the ZrN binder phase provides toughness and thermal stability, achieving both wear resistance and fracture toughness simultaneously
2Reliability
If traditional binder materials are used to maintain toughness, then fracture toughness is maintained, but wear resistance deteriorates at speeds greater than 200 m/min
Solution Approach 1:
The patent modifies the thermal and chemical parameters of the binder phase by using ZrN, which has superior thermal stability and chemical inertness compared to traditional TiN or metal binders. This allows the binder to maintain its structural integrity and bonding strength at high temperatures generated during cutting speeds greater than 200 m/min, thereby maintaining both toughness and wear resistance under extreme operating conditions
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 cutting tool exhibits extended tool life and improved performance at higher speeds, maintaining effectiveness in both continuous and interrupted cutting operations by reducing frictional heat and arresting crack propagation.
Implementation Method 1
frictional heat can cause rapid wear of current tool materials
Implementation Method 2
reduced fracture toughness can become a problem in interrupted cutting because the tool fails by chipping
Data Source
AI summary
A cutting tool having a sintered compact including 30 to 80 vol.% cubic boron nitride and a binder phase, wherein the binder phase includes about 2 to about 6 vol.% ZrN, is disclosed. In more specific examples, the cutting tool has a sintered compact including 30 to 80 vol. % cubic boron nitride, between about 4 vol. % and about 1 5 vol. % aluminum and/or aluminum compound and/or aluminum alloy and/or combinations thereof, and a binder phase, wherein the binder phase includes TiN and about 3 to about 5 vol. % ZrN, and wherein the cubic boron nitride has a grain size of less than 20 microns. Cutting tools of the disclosed composition display improved performance, particularly at higher operating speeds, e.g., about 200 m/min or greater.