Ni-Binder CVD Cutting Tool Coating Without Ni3Ti Interface Phases
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Solution Overview
Problem
The formation of intermetallic phases like Ni3Ti during CVD coating of Ti-containing layers on Ni-containing cemented carbide substrates reduces coating adhesion and wear resistance, posing challenges in developing wear-resistant coatings that can compete with Co-containing cemented carbide substrates.
Innovation Solution
A two-step CVD process for depositing TiN and TiCN layers on Ni-containing cemented carbide substrates, with varying H2/N2 volume ratios in each step, and a subsequent Al2O3 layer, to prevent intermetallic phase formation and achieve high adhesion and fine-grained texture, thereby enhancing wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Ti-containing CVD coating is deposited on Ni-containing cemented carbide substrate, then coating adhesion is improved, but intermetallic phases such as Ni3Ti form at the interface reducing coating adhesion and wear resistance
Solution Approach 1:
The TiN coating is divided into two distinct deposition steps: first step with 1-1.5 vol% TiCl4 and H2/N2 ratio of 0.05-0.18 to prevent Ni3Ti formation, and second step with 2-3 vol% TiCl4 and H2/N2 ratio of 0.8-2.5 to achieve desired coating properties. This segmentation allows the process to avoid intermetallic phase formation while still achieving good adhesion and wear resistance.
Solution Approach 2:
The first deposition step acts as a preliminary action that prepares the substrate surface by depositing TiN under controlled conditions (low H2/N2 ratio) that prevent Ni3Ti intermetallic phase formation. This preliminary layer creates a stable interface before the second deposition step builds the final coating with optimal properties.
2Adaptability or versatility
If high Ni content (60-90 wt%) is used in cemented carbide binder, then alternative to Co binder is achieved, but reactivity with Ti increases causing intermetallic phase formation
Solution Approach 1:
The deposition parameters are specifically adjusted for Ni-containing substrates: TiCl4 concentration (1-3 vol%), H2/N2 ratio (0.05-2.5), temperature (850-900°C), and pressure (300-600 mbar) are optimized to control the chemical reactions at the Ni-Ti interface, preventing Ni3Ti formation while maintaining coating quality.
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 method successfully deposits TiN and TiCN layers with high adhesion and fine grain size on Ni-containing substrates, reducing intermetallic phases and improving wear resistance, including flank wear, flaking resistance, and crater wear in metal cutting operations.
Implementation Method 1
The present invention relates to a coated cutting tool. The cutting tool is CVD coated... wherein the CVD coating comprises an inner layer of TiN, a layer of TiCN and a layer of Al2O3
Data Source
AI summary
A coated cutting tool is provided. The cutting tool is CVD coated and has a substrate of cemented carbide, wherein a metallic binder in the cemented carbide includes Ni. The CVD coating has an inner layer of TiN and a subsequent layer of TiCN and a layer of Al2O3 located between the TiCN layer and an outermost surface of the coated cutting tool.