Large-Dimension Sintered Ceramic Bodies with Controlled-Gap SPS
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Solution Overview
Problem
Existing methods struggle to produce large sintered ceramic bodies with high density, purity, and mechanical strength, particularly for use in plasma processing chambers, due to challenges in controlling temperature gradients and material properties during spark plasma sintering, leading to breakage and poor performance.
Innovation Solution
A spark plasma sintering method using a die and punch arrangement with a controlled gap to manage temperature gradients, combined with specific ceramic powders and graphite materials, to achieve uniform density and purity in ceramic bodies up to 622 mm in size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pressureless vacuum sintering is used to fabricate large dimension ceramic bodies, then the processing is simpler and less equipment-intensive, but the resulting ceramics have lower density, higher porosity, and larger grain sizes leading to reduced mechanical strength and frequent breakage
Solution Approach 1:
The invention changes the sintering parameters by applying high electric current (spark plasma) and uniaxial pressure simultaneously, transforming the traditional pressureless vacuum sintering process. This parameter change enables rapid densification at lower temperatures with shorter holding times, producing fine-grained, high-strength ceramics that are resistant to breakage during handling and processing
Solution Approach 2:
The invention employs periodic pulsed electric current during sintering, where current is applied in pulses to generate localized heating and plasma effects that promote rapid densification. This periodic action allows controlled sintering with minimal grain growth, achieving high density and fine microstructure that prevent breakage in large dimension ceramics
2Manufacturing precision
If sintering aids are used to promote densification, then the densification improves, but the purity of the ceramic decreases and electrical, magnetic or other properties are altered in undesirable manners
Solution Approach 1:
The invention extracts or removes the need for sintering aids from the sintering process by employing spark plasma sintering technology. The high energy density and rapid heating rate of SPS enable effective densification without requiring additional chemical additives, thereby maintaining the inherent purity of the ceramic material and preserving its electrical, magnetic and other functional properties
Solution Approach 2:
The invention replaces the chemical mechanism of sintering aids with a physical/mechanical mechanism of spark plasma heating and pressure application. This substitution eliminates the need for chemical additives that would contaminate the ceramic, achieving densification through controlled energy input and mechanical pressure instead of chemical reactions
3Adaptability or versatility
If ceramic materials are prepared at large dimensions (>100 mm), then the applicability for semiconductor processing chambers improves, but the risk of breakage during sintering, cooling, post-sintering treatments or handling increases
Solution Approach 1:
The invention performs preliminary densification and strength development during the sintering process itself by applying high pressure and spark plasma heating. This preliminary action creates a strong, dense microstructure before the ceramic enters the cooling and post-processing stages, making large dimension parts resistant to breakage during subsequent handling, machining, or assembly operations
Solution Approach 2:
The invention changes the thermal and mechanical parameters during sintering by applying rapid heating rates, high pressure, and controlled holding times. These parameter changes produce fine-grained, homogeneous microstructures with high strength that prevent breakage in large dimension ceramics throughout the entire manufacturing cycle including cooling and post-sintering treatments
4Loss of time
If conventional sintering methods are used for large dimension ceramics, then the processing time is extended to several days, but the resulting density is still unacceptable at less than 95% of theoretical density
Solution Approach 1:
The invention rushes through the sintering process by applying high energy density spark plasma and uniaxial pressure, completing densification in minutes rather than days. This rapid sintering skips the extended time periods of conventional methods while achieving superior density (>98% theoretical density) through intense localized heating and pressure that promotes rapid atomic diffusion and pore elimination
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 method enables the production of large, high-purity, and high-density ceramic bodies with reduced breakage risk, suitable for plasma processing chambers, exhibiting low porosity and uniform density variation, enhancing mechanical properties and resistance to plasma etch.
Implementation Method 1
spark plasma sintering
Implementation Method 2
spark plasma sintering
Implementation Method 3
gap between each of the upper punch and the lower punch and the inner wall of the die
Implementation Method 4
manage temperature gradients
Implementation Method 5
sintering the ceramic powder to form the sintered ceramic body
Data Source
AI summary
A method of making a sintered ceramic body comprising the steps of disposing a ceramic powder (5) inside an inner volume of a spark plasma sintering tool (1), wherein the tool comprises: a die (2) comprising a sidewall comprising inner and outer walls, wherein the inner wall has a diameter defining the inner volume; upper and lower punches (4,4′) operably coupled with the die, wherein each of the punches have an outer wall defining a diameter less than the diameter of the die inner wall, thereby creating a gap (3) between the punches and the inner wall when at least one of the punches are moved within the inner volume, and the gap is from 10 μm to 70 μm wide; creating vacuum conditions inside the inner volume; moving at least one of the punches to apply pressure to the ceramic powder while heating, and sintering; and lowering the temperature of the sintered body.