Spark Plasma Sintering Tool With Punch Gap for Large Ceramic Densification
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Solution Overview
Problem
Existing methods struggle to produce large sintered ceramic bodies with high density, purity, and mechanical strength, as they often result in breakage, high porosity, and unsuitable properties for applications like plasma processing chambers due to temperature gradients and material incompatibilities.
Innovation Solution
A spark plasma sintering tool with a die and punches that create a controlled temperature distribution by maintaining a gap between the die and punches, using conductive graphite materials to ensure homogeneous heating and cooling of ceramic powders, allowing for dimensions up to 625 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pressure-less vacuum sintering is used to densify refractory ceramic materials, then the materials can be sintered at high temperatures, but the resulting sintered ceramic has lower density and higher porosity
Solution Approach 1:
The patent replaces conventional pressure-less vacuum sintering with field-assisted sintering technology (FAST), also known as spark plasma sintering (SPS). This substitution introduces electrical fields and pulsed currents to enable rapid heating and densification at lower temperatures, achieving >95% theoretical density while avoiding the porosity issues of traditional methods
Solution Approach 2:
The patent fundamentally changes the sintering parameters by applying pulsed electrical currents with frequencies of 1-10 kHz and temperatures ranging from 1000-2000°C for durations of 1-30 minutes. These parameter changes enable rapid heating rates of 10-1000°C/min, achieving high density without the extended time and temperature requirements of conventional sintering
2Duration of action of moving object
If conventional sintering is used to prepare large dimension ceramic bodies, then the processing time is extended, but the mechanical strength and density remain insufficient
Solution Approach 1:
The patent replaces time-consuming conventional sintering with field-assisted sintering technology that uses pulsed electrical currents to achieve rapid densification. This substitution reduces sintering time from days to minutes while simultaneously improving mechanical strength through uniform heating and controlled pressure application
Solution Approach 2:
The patent employs periodic pulsed electrical currents with frequencies of 1-10 kHz during the sintering process. These periodic pulses generate localized heating at particle interfaces through electrical breakdown and Joule heating, enabling rapid and uniform densification that improves mechanical strength while reducing overall processing time
3Manufacturing precision
If sintering aids are used to promote densification, then the densification is improved, but the purity of the sintered ceramic is compromised
Solution Approach 1:
The patent replaces chemical sintering aids with field-assisted sintering technology that uses electrical fields and pulsed currents to promote densification. This substitution achieves >95% theoretical density through field-induced heating and pressure without introducing any foreign chemical substances, thereby maintaining 99.99% purity
Solution Approach 2:
The patent enables the ceramic powder to densify through self-heating caused by electrical breakdown and Joule heating at particle interfaces during field-assisted sintering. This self-service mechanism eliminates the need for external sintering aids while achieving complete densification, maintaining both high density and high purity
4Length of stationary object
If large dimension ceramic bodies are prepared by conventional methods, then the size is increased, but the risk of breakage increases
Solution Approach 1:
The patent replaces conventional slow sintering with field-assisted sintering that uses pulsed electrical currents to achieve rapid and uniform heating throughout large dimension samples. This substitution prevents temperature gradients and thermal stresses that cause breakage, enabling successful sintering of samples up to 200 mm in diameter with minimal defect formation
Solution Approach 2:
The patent applies continuous pulsed electrical currents throughout the sintering process to maintain uniform heating and densification across large dimension samples. This continuous action prevents localized overheating and thermal gradients, reducing the risk of thermal shock and breakage during and after sintering
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 tool enables the production of large sintered ceramic bodies with reduced breakage risk, high density, and improved mechanical properties, suitable for plasma-resistant applications.
Implementation Method 1
The main characteristic of SPS is that the pulsed or un-pulsed DC or AC current directly passes through the graphite die, as well as the powder compact, in the case of conductive samples. Joule heating has been found to play a dominant role in the densification of powder compacts
Implementation Method 2
Spark plasma sintering (SPS) technology has been proposed as a solution to fabricate ceramic bodies of large dimension
Implementation Method 3
using conductive graphite materials to ensure homogeneous heating and cooling of ceramic powders
Implementation Method 4
Preparation or fabrication of ceramic parts at large dimensions of about 100 mm to 200 mm and greater proves challenging
Data Source
AI summary
A spark plasma sintering tool. The tool comprises a die including an inner wall having a diameter that defines an inner volume configured to receive a ceramic powder, and an upper punch and a lower punch operably coupled with the die, wherein each of the upper and lower punches have an outer wall defining a diameter that is less than the diameter of the inner wall of the die thereby creating a gap from 10 μm to 100 μm wide between each of the punches and the inner wall of the die when at least one of the punches moves within the inner volume of the die. Also disclosed is a method of using the tool to create a large sintered ceramic body and a computer readable medium storing processor-executable instructions adapted to cause one or more computing devices to operate the tool.