MTCVD Ti(C,N) Coated Cutting Tool for Flaking Resistance

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Solution Overview

Problem

Cutting tools for chip forming machining of metals face challenges with wear resistance, particularly flaking resistance, especially in demanding applications like turning in nodular cast iron, where existing CVD coatings exhibit insufficient oxidation resistance and thermal crack susceptibility.

Innovation Solution

A coated cutting tool with a substrate coated using a moderate temperature chemical vapor deposition (MTCVD) Ti(C,N) layer having a specific grain width and carbon-to-nitrogen atomic ratio, combined with an alumina layer, providing improved wear resistance and thermal crack resistance through a tailored layer structure and texture coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If MTCVD process is used to deposit Ti(C,N) coating, then edge chipping resistance is improved, but flaking resistance deteriorates

Engineering Contradiction:

Improveedge chipping resistanceVSAvoidflaking resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the deposition temperature parameter from high temperature (HTCVD) to moderate temperature (MTCVD) range, and adjusts the precursor chemistry (using acetonitrile) to achieve a unique microstructure with columnar grains and (422) texture that simultaneously improves edge chipping resistance while maintaining adequate flaking resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating structure with multiple layers including Ti(C,N) layers with specific microstructures, TiN layers, and alumina layers, where each layer contributes different properties to achieve both improved edge chipping resistance and acceptable flaking resistance

Inventive Principle:

Principle #40Composite materials

2Strength

If CVD coating is applied to cutting tool, then wear resistance is improved, but oxidation resistance deteriorates

Engineering Contradiction:

Improvewear resistanceVSAvoidoxidation resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies a composite coating system where Ti(C,N) layers provide wear resistance through their hard microstructure, while TiN and alumina layers provide oxidation resistance, creating a multi-functional protective coating that addresses both requirements simultaneously

Inventive Principle:

Principle #40Composite materials

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 enhances the cutting tool's flaking resistance and thermal crack resistance, leading to improved performance in milling applications, particularly in grey and nodular cast iron, with a smoother surface and increased toughness.

Implementation Method 1

a substrate having a surface coated with a chemical vapor deposition (CVD)

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUSRE49475E1Coated cutting tool

Publication Date: 2023.03.28 SANDVIK INTELLECTUAL PROPERTY AB

AI summary

A coated cutting tool having a substrate and a surface coating, wherein the coating includes a Ti(C,N) layer of at least one columnar fine-grained MTCVD Ti(C,N) layer with an average grain width of 0.05-0.2 μm and an atomic ratio of carbon to the sum of carbon and nitrogen (C/(C+N)) contained in the MTCVD Ti(C,N) layer is in average 0.50-0.65.