Sintered Ceramic Gas Nozzle with Graded Crystal Grain Structure
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Solution Overview
Problem
Existing gas nozzles made of sintered ceramics used in plasma processes experience significant particle generation due to exposure to corrosive gases, with previous solutions offering only limited effectiveness in reducing this issue.
Innovation Solution
A gas nozzle design featuring a fired surface with a first region near the outlet having a smaller average crystal grain size compared to a second region deeper inside, where the grain size is 1.2 times or less, effectively reducing particle generation by enhancing the mechanical strength and resistance to plasma exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the average crystal grain size in the first region (outlet vicinity) is made larger, then particle generation is reduced, but mechanical strength decreases
Solution Approach 1:
The gas nozzle applies local quality by creating different crystal grain sizes in different regions: the first region (outlet vicinity) has larger crystal grains to reduce particle generation, while the second region (inner portion) has smaller crystal grains to maintain mechanical strength. This spatial differentiation of material properties resolves the contradiction between reducing particles and maintaining strength.
2Strength
If the average crystal grain size in the second region (inner portion) is made smaller, then mechanical strength is increased, but particle generation reduction effect is weakened
Solution Approach 1:
The invention applies local quality by specifying that the second region (inner portion) should have smaller crystal grains than the first region, creating a gradient structure. This local differentiation ensures that each region optimizes for its specific function: the outlet region minimizes particles while the inner region provides structural strength.
3Strength
If the crystal grain size is uniformly small throughout, then mechanical strength is maximized, but particle generation is not sufficiently reduced
Solution Approach 1:
The invention resolves this contradiction by abandoning uniform crystal grain size and instead implementing local quality with a gradient structure. The first region near the outlet has larger grains for particle reduction, while the second region has smaller grains for strength, optimizing both properties simultaneously through spatial differentiation.
4Object-generated harmful factors
If the crystal grain size is uniformly large throughout, then particle generation is reduced, but mechanical strength and resistance to thermal stress decrease
Solution Approach 1:
The invention applies local quality by creating a crystal grain size gradient where the outlet region has larger grains for particle reduction while the inner region has smaller grains for thermal stress resistance. This spatial differentiation allows each region to optimize for its specific operational requirements.
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 design significantly reduces particle generation by minimizing the average crystal grain size near the outlet and maintaining a stable grain size distribution further inside, thereby improving the nozzle's performance and durability under plasma exposure.
Implementation Method 1
The material of the gas nozzle is typically sintered yttria or sintered alumina, which has excellent corrosion resistance.
Data Source
AI summary
A gas nozzle having a fired surface excellent in particle reduction effect is provided. The gas nozzle 1 is a columnar gas nozzle made of sintered ceramics, provided with at least one through-hole 2 through which gas flows. The entire inner surface 2a of the through-hole 2 and the end face 1A on which outlet 2b of the through-hole 2 is provided are both fired surfaces. The inner surface 2a of the through-hole 2 has a first region A in the vicinity of the outlet 2b and a second region B which is located at a further position than the first region A. The average crystal grain size in the first region A is formed to be smaller than the average crystal grain size in the second region B.