TiB2-Coated Cutting Tool With Graded TiBN Transition Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing coated tools with fine-grained titanium diboride layers face challenges in achieving optimal layer adhesion and stability, particularly in cutting machining of metallic materials, due to large residual stress steps and potential formation of hexagonal phases in the titanium boronitride transition layer.
Innovation Solution
A coated tool design featuring a substrate with a layer structure of titanium nitride, titanium boronitride transition layer, and titanium diboride, where the boron content in the transition layer increases up to 15 at.-%, avoiding hexagonal phase formation and enhancing adhesion, with a titanium boronitride transition layer thickness of 0.1-4.0 μm and titanium diboride layer thickness of 0.2-15.0 μm, optimized for residual stresses and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fine-grained titanium diboride layer is deposited directly on the substrate, then wear resistance is improved, but layer adhesion deteriorates due to large residual stress steps
Solution Approach 1:
A titanium boronitride transition layer is introduced between the titanium nitride layer and the titanium diboride layer. This intermediate layer has a boron content that increases from the titanium nitride layer toward the titanium diboride layer, creating a gradual compositional transition that reduces residual stress steps and improves layer adhesion while maintaining wear resistance
Solution Approach 2:
The boron content in the transition layer is gradually increased from the titanium nitride layer toward the titanium diboride layer, creating a continuous parameter change that reduces the abrupt residual stress step. The boron content is controlled to not exceed 15 at.-% to avoid hexagonal phase formation while still achieving stress reduction
2Reliability
If boron content in the transition layer is increased to improve adhesion, then layer adhesion improves, but hexagonal phase formation occurs which adversely affects coating properties
Solution Approach 1:
The boron content in the transition layer is precisely controlled to increase gradually but remain below 15 at.-%, which is the threshold for hexagonal phase formation. This parameter control allows the transition layer to reduce residual stresses and improve adhesion while maintaining the stable cubic crystal structure throughout
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
This configuration significantly improves layer adhesion and stability, preventing hexagonal phase formation, ensuring better bonding and wear resistance, especially suitable for cutting titanium alloys and other nonferrous alloys, with enhanced machining performance.
Implementation Method 1
a disadvantageous large step change in the residual stresses in the hard material coating at the boundary to the titanium diboride layer is avoided
Implementation Method 2
EP 2 209 929 B1 describes a tool for cutting machining comprising a substrate material and a hard material coating which has been deposited on the substrate material and comprises a titanium diboride layer
Data Source
AI summary
A coated tool has a substrate and a hard material coating deposited on the substrate. The hard material coating has a layer structure in the following order, starting from the substrate: a titanium nitride layer, a titanium boron nitride transition layer, and a titanium diboride layer. The titanium boron nitride transition layer has a boron content that increases from the titanium nitride layer in the direction of the titanium diboride layer. The boron content does not exceed 15 at %.