Arc PVD Target Composite for Droplet Reduction
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Solution Overview
Problem
PVD processes, particularly arc evaporation, suffer from macroparticle formation leading to undesirable roughness and reduced hardness in aluminum oxide coatings due to the detachment of metallic droplets at lower temperature zones around the arc impact point, limiting the deposition of the wear-resistant alpha phase.
Innovation Solution
A target composed of aluminum oxide and elemental chromium, or aluminum nitride with chromium in a ceramic compound, is used for arc evaporation, where chromium is present in various forms to achieve a higher melting point, reducing droplet formation and enhancing coating quality by incorporating up to 70 at% chromium in ceramic forms, thereby minimizing macroparticle detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If arc evaporation is used to deposit aluminum oxide layers, then a high proportion of the wear-resistant alpha phase is achieved, but macroparticles (droplets) are formed causing undesirable roughness and reduced hardness
Solution Approach 1:
The patent uses a composite target material consisting of aluminum oxide ceramic particles embedded in a chromium metal matrix. This composite structure allows the aluminum oxide to evaporate and form the desired alpha phase coating while the chromium matrix prevents droplet formation by providing a higher melting point framework that stabilizes the deposition process.
Solution Approach 2:
The patent changes the physical and chemical parameters of the target material by incorporating chromium in ceramic forms (chromium oxide, chromium carbide, chromium nitride) with melting points exceeding 1000°C. This parameter change raises the overall melting point of the target material, preventing the formation of macroparticles and droplets during arc evaporation while maintaining the deposition of fine alpha phase particles.
2Ease of manufacture
If elemental chromium is used in the target, then the deposition process is simplified, but droplet formation occurs due to lower melting temperature
Solution Approach 1:
The patent creates a composite target where chromium is combined with aluminum oxide ceramic particles. This composite structure maintains the ease of manufacturing chromium-based targets while the aluminum oxide ceramic component raises the effective melting point, preventing droplet formation during arc evaporation.
Solution Approach 2:
The patent modifies the temperature parameter of the target material by incorporating chromium in ceramic forms (oxide, carbide, nitride) with melting points above 1000°C. This parameter change prevents the target material from melting and forming droplets during the arc evaporation process, while still allowing chromium to be deposited in the desired coating.
3Manufacturing precision
If magnetron sputtering is used, then uniform coating is produced with fine particle detachment, but the process gas flow is difficult to regulate and alpha phase proportion is reduced
Solution Approach 1:
The patent replaces the magnetron sputtering process with arc evaporation using a composite target. This substitution eliminates the gas flow control difficulties inherent in magnetron sputtering while maintaining the ability to produce uniform coatings. The arc evaporation process inherently provides the energy needed to detach fine particles and deposit the alpha phase without requiring complex gas flow regulation.
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 significantly reduces droplet formation, improves coating quality, and achieves a high proportion of the thermodynamically stable alpha phase, resulting in coatings with high hardness, wear resistance, and thermal shock resistance.
Implementation Method 1
In the PVD process, different variants are used to evaporate the material to be deposited. PVD processes including cathode sputtering (sputter deposition), arc evaporation (arc PVD)... the arc on the target generates very high temperatures on the order of several thousand degrees Celsius, which lead to the desired evaporation or sublimation of the target material for deposition on the substrate
Implementation Method 2
around the point of impact of the arc, zones of lower temperature arise, for example in the range of 500 to 1000 ° C, in which macroparticles, so-called droplets, are detached from some target metals
Data Source
AI summary
Target for the deposition of solid solution layers comprising at least two different metals on a substrate by means of arc physical vapour deposition (arc PVD), wherein the target comprises at least two different metals. In order to produce solid solution layers which are as free as possible of macroparticles (droplets), according to the invention at least the metal with the lowest melting temperature is present in the target in a ceramic compound, specifically as a metal oxide, metal carbide, metal nitride, metal carbonitride, metal oxynitride, metal oxycarbide, metal oxycarbonitride, metal boride, metal boronitride, metal borocarbide, metal borocarbonitride, metal borooxynitride, metal borooxocarbide, metal borooxocarbonitride, metal oxoboronitride, metal silicate or a mixture thereof, and at least one metal which differs from the metal with the lowest melting temperature is present in the target in elemental (metallic) form.