PVD-Coated Cutting Tools CVD Base Conductive Layer
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Solution Overview
Problem
Ceramic and polycrystalline cubic boron nitride (PCBN) substrates are difficult to coat using physical vapor deposition (PVD) due to their low electrical conductivity, requiring pre-treatment like plasma etching, which complicates the coating process.
Innovation Solution
A chemical vapor deposition (CVD) base coating scheme with electrically conductive properties is applied to the substrate, enabling a PVD coating process by providing a conductive layer, which includes inner and outer mediate coating layers of nitrides and carbides, facilitating the PVD coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If PVD coating is applied directly to ceramic or PCBN substrates, then the coating process should be simple, but the low electrical conductivity of these substrates requires pre-treatment like plasma etching which complicates the process
Solution Approach 1:
A CVD base coating layer is applied to the ceramic or PCBN substrate before the PVD coating process. This preliminary CVD layer provides the necessary electrical conductivity and surface properties that enable successful PVD coating without requiring plasma etching pre-treatment, thus simplifying the overall process while ensuring reliable coating adhesion
Solution Approach 2:
The CVD base coating layer acts as an intermediary between the non-conductive ceramic/PCBN substrate and the PVD coating process. This intermediate layer facilitates the PVD deposition by providing electrical conductivity and appropriate surface characteristics, eliminating the need for complex pre-treatment steps
2Reliability
If plasma etching pre-treatment is applied to enable PVD coating, then coating adhesion is improved, but the coating process becomes more complex and time-consuming
Solution Approach 1:
The CVD base coating is applied in advance to create a conductive surface that is inherently suitable for PVD coating. This preliminary action eliminates the need for time-consuming plasma etching steps, thereby improving coating adhesion while simultaneously increasing overall coating process efficiency and productivity
Solution Approach 2:
The invention extracts and eliminates the plasma etching pre-treatment step from the coating process. By using a CVD base coating that inherently provides the necessary surface properties, the harmful and time-consuming plasma etching step is removed, streamlining the process while maintaining coating adhesion
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 approach allows for effective PVD coating of ceramic and PCBN substrates without the need for pre-treatment, enhancing the coating process's efficiency and consistency.
Implementation Method 1
A base coating scheme is applied by chemical vapor deposition to the substrate surface wherein the base coating scheme includes the following coating layers: an inner coating layer adjacent to the substrate surface wherein the inner coating layer is a nitride selected from the group consisting of titanium nitride, zirconium nitride and hafnium nitride
Implementation Method 2
An exterior coating scheme is deposited on the base coating scheme by physical vapor deposition
Data Source
AI summary
A coated cutting insert includes a substrate that is either a ceramic substrate or polycrystalline cubic boron nitride-containing substrate and has a substrate surface. A base coating scheme is applied by chemical vapor deposition to the substrate surface wherein the base coating scheme includes the following coating layers: an inner coating layer adjacent to the substrate surface wherein the inner coating layer is a nitride selected from the group consisting of titanium nitride, zirconium nitride and hafnium nitride; an inner mediate coating layer deposited to the inner coating layer wherein the inner mediate coating layer is a carbonitride selected from the group consisting of titanium carbonitride, zirconium carbonitride and hafnium carbonitride; an outer mediate coating layer deposited to the inner mediate coating layer and wherein the outer mediate coating layer is a carbonitride selected from the group consisting of titanium carbonitride, zirconium carbonitride and hafnium carbonitride; and an outer coating layer deposited on the outer mediate coating layer wherein the outer coating layer is a carbide selected from the group consisting of titanium carbide, zirconium carbide and hafnium carbide. An exterior coating scheme is deposited on the base coating scheme by physical vapor deposition.