AlVN Coating Microalloyed with Ti and Si for High-Temperature Stability
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Solution Overview
Problem
Metastable c-TM-Al-N coatings exhibit limited thermal stability and hardness loss at annealing temperatures above 900°C due to decomposition, restricting their application to maximum temperatures of 800°C for longer exposure times and 900°C for short exposure times, which is inadequate for high-temperature applications like hot metal working and turbine tipping sealants.
Innovation Solution
A high-temperature stable ceramic coating structure comprising Al, V, and N microalloyed with Ti and Si, produced by gas phase deposition, which maintains hardness and fracture toughness above 900°C, even after phase transformation, and can be used for extended exposure times without significant hardness loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metastable c-TM-Al-N coatings are used for wear resistant applications, then hardness and fracture resistance are improved, but thermal stability deteriorates at annealing temperatures above 900°C due to decomposition
Solution Approach 1:
The patent applies parameter changes by modifying the alloy composition parameters - specifically adding microalloying elements Ti and Si in controlled amounts (0.1-5 at.% each) to the AlVN coating system. This compositional parameter change transforms the coating's thermal behavior, enabling it to maintain hardness above 900°C where conventional metastable coatings decompose. The parameter change resolves the contradiction by altering the material's fundamental properties rather than changing processing conditions.
Solution Approach 2:
The patent employs composite materials by creating a multi-element alloy system AlVN microalloyed with Ti and Si. This composite approach combines the beneficial effects of different elements: AlVN provides the base hardness and wear resistance, while Ti and Si microalloying elements suppress decomposition and enhance high-temperature stability. The composite material structure allows the coating to simultaneously achieve high hardness and exceptional thermal stability, resolving the contradiction between strength and compositional stability.
2Productivity
If metastable c-TM-Al-N coatings are applied to extend tool life in cutting and forming applications, then productivity is improved, but application temperature is limited to maximum 800°C for long exposure times
Solution Approach 1:
The patent uses parameter changes by modifying the coating composition to enable operation at higher temperatures. The AlVN base alloy with Ti and Si microalloying changes the thermal decomposition parameters, allowing the coating to maintain its wear protective function at temperatures up to 1000°C and above, thereby extending the applicable temperature range while maintaining productivity benefits.
Solution Approach 2:
The patent extends the operational envelope by adding a temperature dimension - moving from the conventional 800°C maximum to over 1000°C capability. This dimensional expansion in temperature space allows the same coating to provide productivity enhancement in previously inaccessible high-temperature applications such as hot metal working and turbine sealants.
3Strength
If microalloying elements Ti and Si are added to AlVN coating, then hardness and fracture toughness are enhanced above 900°C, but coating composition complexity increases
Solution Approach 1:
The patent applies local quality by using trace amounts (microalloying levels of 0.1-5 at.%) of Ti and Si elements rather than bulk additions. This localized, minimal incorporation of alloying elements provides the necessary hardening and toughness enhancement at high temperatures without significantly complicating the overall coating composition or deposition process. The microalloying approach achieves maximum benefit with minimum complexity.
Solution Approach 2:
The patent optimizes the composition parameters by precisely controlling the microalloying element concentrations within specific ranges (0.1-5 at.% for Ti and Si). This parameter optimization ensures that the coating achieves enhanced hardness and fracture toughness above 900°C while maintaining compositional simplicity and ease of manufacture. The defined parameter ranges prevent excessive complexity while achieving the desired performance enhancement.
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 AlVN microalloyed with Ti and Si coating structure demonstrates enhanced hardness and fracture toughness above 900°C, allowing for stable operation up to 100 hours at 800°C and beyond, making it suitable for demanding high-temperature applications with prolonged exposure.
Implementation Method 1
a high-temperature stable ceramic coating structure comprising Al, V, and N microalloyed with Ti and Si, produced by gas phase deposition
Implementation Method 2
the coating structure is in multiphase form at least above a temperature of 900° C., in particular in cubic phase and wurtzite phase form
Data Source
AI summary
The present invention discloses a high-temperature stable ceramic coating structure including a microalloy comprising the elements Al, V and N producible by a gas phase deposition process.