Hard Material Workpiece Multilayer Coating for High-Temperature Wear
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Solution Overview
Problem
Existing cutting and milling tools face challenges with high temperature wear resistance, thermal stability, and mechanical properties, particularly in machining high-hardness metals, as (Al,Ti)N coatings decompose at elevated temperatures, leading to reduced tool life and performance.
Innovation Solution
A workpiece with a hard material layer comprising a first and second metal nitride layer, each with specific compositions and optional alloying elements, stacked to enhance thermal stability, hardness, and fracture toughness, using physical vapor deposition or chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If (Al,Ti)N coating is used to improve wear resistance and temperature resistance, then tool lifetime is extended, but the coating decomposes at elevated temperatures (about 900°C) into c-TiN and h-AlN, reducing thermal stability
Solution Approach 1:
The patent modifies the composition parameters of the (Al,Ti)N coating by adding specific alloying elements (Ta, Mo, W, Nb, Si, B) within defined concentration ranges. These compositional changes shift the decomposition temperature to higher values, improving thermal stability while maintaining the coating's protective functions and extending tool lifetime.
Solution Approach 2:
The patent creates a composite coating system by combining (Al,Ti)N with multiple alloying elements forming a complex multi-element nitride system. This composite structure leverages the synergistic effects of different elements to enhance both wear resistance and thermal stability, preventing decomposition at elevated temperatures.
2Reliability
If coating thickness is increased to improve protection and extend tool life, then wear resistance improves, but thermal load accumulation increases, potentially reducing tool performance
Solution Approach 1:
The patent optimizes the thickness parameter within a specific range (1 μm to 10 μm) to achieve the desired balance. This controlled thickness provides sufficient wear protection while limiting thermal load accumulation, maintaining tool performance at high temperatures.
3Productivity
If machining speed is increased to improve productivity, then output increases, but tool temperature rises, accelerating coating decomposition and reducing tool life
Solution Approach 1:
The patent modifies the coating's chemical composition by incorporating alloying elements that raise the decomposition temperature. This allows the tool to operate at higher temperatures generated by increased machining speeds without suffering from accelerated coating decomposition, thereby enabling higher productivity.
4Stability of the object's composition
If alloying elements are added to improve thermal stability and shift decomposition temperature, then thermal stability improves, but coating composition complexity increases, potentially affecting manufacturing precision
Solution Approach 1:
The patent defines specific concentration ranges for each alloying element (e.g., Ta: 0-15 at.%, Mo: 0-15 at.%, W: 0-10 at.%, Nb: 0-15 at.%, Si: 0-30 at.%, B: 0-7 at.%) to achieve thermal stability improvements while maintaining manufacturability. These controlled parameter specifications enable precise composition control during deposition processes.
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 multi-layered nitride structure significantly improves tool life and performance by maintaining mechanical and thermal properties at high temperatures, offering enhanced wear resistance and oxidation resistance, with a lifetime increase of about three times compared to non-inventive combinations.
Implementation Method 1
A method of manufacturing a workpiece comprising a substrate and a hard material layer disposed over the substrate uses physical vapor deposition and/or chemical vapor deposition to generate the hard material layer over the substrate
Implementation Method 2
A method of manufacturing a workpiece comprising a substrate and a hard material layer disposed over the substrate uses physical vapor deposition and/or chemical vapor deposition to generate the hard material layer over the substrate
Implementation Method 3
The technological benefits of (Al,Ti)N and its excellent physical properties, especially at elevated temperatures, is partly explained in terms of a spinodal decomposition process during which cubic (Al,Ti)N decomposes iso-structurally into coherent cubic c-AlN and c-TiN-enriched domains
Implementation Method 4
The combination of elastic properties and a lattice mismatch between coherent c-AlN and c-TiN-enriched domains leads to significant age hardening. During the age-hardening process, the hardness of (Al,Ti)N thin layers has been shown to increase up to 10%
Implementation Method 5
Annealing at higher temperatures leads to the transformation of c-AlN into the thermodynamically stable hexagonal (also referred to as wurtzite) structure, h-AlN, resulting in a dual phase structure comprising c-TiN and h-AlN with reduced mechanical properties
Data Source
Figure 1~2
Figure 3A~4
Figure 5
AI summary
A workpiece includes a substrate and a hard material layer disposed over the substrate. The hard material layer comprises at least one first metal nitride layer and at least one second metal nitride layer disposed one over the other. The first metal nitride layer has a composition (Tia, Sib, Zz) CpN1-p with optionally added alloying elements Z = (Ni,Ta,Mo,W,Nb,Al), with 0 ≤ Ni ≤ 9 at.%, 0 ≤ Ta ≤ 15 at.%, 0 ≤ Mo ≤ 15 at.%, 0 ≤ W ≤ 10 at.%, 0 ≤ Nb ≤ 15 at.%, 0 ≤ Al ≤ 40 at.%. The second metal nitride layer has a composition (Alc, Tid, Xx, Be)CpN1-p with optionally added alloying elements X = (Ni,Ta,Si,Mo,W,Nb), with 0 ≤ Ni ≤ 20 at.%, 0 ≤ Ta ≤ 15 at.%, 0 ≤ Si ≤ 30 at.%, 0 ≤ Mo ≤ 12 at.%, 0 ≤ W ≤ 10 at.%, 0 ≤ Nb ≤ 15 at.%, wherein 0.50 ≤ a ≤ 0.90, 0.05 ≤ b ≤ 0.32, 0.30 ≤ c ≤ 0.72, 0.20 ≤ d ≤ 0.50, 0.01 ≤ e ≤ 0.07. The compositions of the first metal nitride layer and the second metal nitride layer are approximately stoichiometric, C can be partially or completely replaced by O, and 0.00 ≤ p ≤ 0.05 for the first metal nitride layer and 0.00 ≤ p ≤ 0.05 for the second metal nitride layer.