W-Ni Sputtering Target Composition for Homogeneous Electrochromic Coatings
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Solution Overview
Problem
Current methods for producing W--Ni sputtering targets, such as thermal spraying, result in ferromagnetic impurities, limited material density, and non-uniform layers due to intermetallic phases, which affect the homogeneity and stability of electrochromic layers in displays and smart glass applications.
Innovation Solution
A process for producing a W--Ni sputtering target with a composition of 45-75% W and balance Ni, minimizing intermetallic phases to less than 10% by area, and achieving high purity and fine-grained microstructure through powder-metallurgical methods, including compacting and cooling steps, and thermomechanical treatments to ensure optimal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal spraying is used to produce W-Ni sputtering targets, then production efficiency is improved, but ferromagnetic impurities and intermetallic phases are introduced that worsen layer homogeneity
Solution Approach 1:
The patent removes the problematic thermal spraying step that introduces ferromagnetic impurities and intermetallic phases. Instead, it uses a direct powder metallurgy approach with controlled sintering to produce the W-Ni alloy target without the harmful byproducts of thermal spraying, thereby extracting the harmful process step while maintaining production efficiency.
Solution Approach 2:
The patent changes the key process parameters from thermal spraying to controlled sintering at specific temperatures (900-1100°C) with controlled atmosphere. This parameter change eliminates the formation of intermetallic phases while maintaining high production efficiency, resolving the contradiction between productivity and layer homogeneity.
2Productivity
If thermal spraying is used to produce W-Ni sputtering targets, then production speed is improved, but material density is limited which worsens coating rates
Solution Approach 1:
The patent changes the densification mechanism from thermal spraying to controlled sintering at optimized temperatures and pressures. This parameter change achieves higher material density (≥95% theoretical density) while maintaining fast production speed, thereby improving coating rates without sacrificing productivity.
Solution Approach 2:
The patent creates a composite microstructure through controlled sintering that achieves high density while maintaining the desired W-Ni alloy composition. The controlled sintering process produces a dense, homogeneous microstructure that improves coating rates compared to the porous structure from thermal spraying.
3Strength
If intermetallic phases are present in the target material, then certain mechanical properties are improved, but coating uniformity is worsened due to different sputtering rates
Solution Approach 1:
The patent changes the phase composition parameters by controlling the sintering process to avoid intermetallic phase formation. By adjusting temperature (900-1100°C), time, and atmosphere parameters, the process produces a homogeneous α-phase W-Ni alloy structure that ensures uniform sputtering rates and coating uniformity while maintaining adequate mechanical properties.
Solution Approach 2:
The patent achieves homogeneous phase distribution and composition throughout the target material through controlled sintering. This homogeneity eliminates the sputtering rate variations caused by intermetallic phases, ensuring uniform coating deposition while the controlled process maintains necessary mechanical strength.
4Reliability
If the target contains ferromagnetic regions, then magnetic properties are enhanced, but coating homogeneity is worsened due to different coating rates
Solution Approach 1:
The patent changes the magnetic properties parameter by controlling the Ni content (4-20 at%) and sintering parameters to achieve the desired magnetic characteristics without forming ferromagnetic regions. The controlled sintering process produces a paramagnetic or weakly ferromagnetic homogeneous structure that maintains coating homogeneity while providing sufficient magnetic properties for the application.
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 resulting W--Ni sputtering target provides homogeneous and stable electrochromic layers with improved switching behavior and extended target life, reducing ferromagnetic impurities and intermetallic phase-related issues, leading to enhanced coating uniformity and mechanical properties.
Implementation Method 1
sputtering targets composed of W—Ni alloys which are ablated by reactive magnetron sputtering under oxygen to form W—Ni mixed oxide layers
Implementation Method 2
a compacting and sintering step, and a cooling step
Data Source
AI summary
A process for producing a W—Ni sputtering target includes providing the sputtering target with 45 to 75 wt % W and a remainder of Ni and common impurities. The sputtering target contains a Ni(W) phase, a W phase and no or less than 10% by area on average of intermetallic phases measured at a target material cross section.