Silicon Carbide-Graphite Composite Thermal Shock Resistance
Solution Overview
Problem
Graphite components used in LED manufacturing and ion implantation applications face issues with chemical resistance, tribological properties, and thermal shock resistance due to the mismatch in thermal expansion coefficients between graphite and silicon carbide coatings, leading to erosion and delamination.
Innovation Solution
A silicon carbide-graphite composite is developed with an interpenetrating structure where the interior bulk graphite material is coated with an exterior silicon carbide matrix, characterized by specific thickness ratios, grain sizes, and thermal expansion coefficients, formed through chemical vapor conversion to enhance thermal shock resistance and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon carbide coating is applied on graphite components, then chemical resistance and tribological properties are improved, but thermal shock resistance deteriorates due to CTE mismatch causing delamination
Solution Approach 1:
The patent applies composite materials by creating an interpenetrating phase composite where silicon carbide and graphite form a mutually interpenetrating continuous network structure. This composite structure combines the chemical resistance of SiC with the thermal shock resistance of graphite, eliminating delamination issues while maintaining protective properties. The interpenetrating phases allow both materials to coexist structurally, with each phase providing its inherent benefits without the weaknesses of separate coating systems.
2Strength
If silicon carbide coating is applied on graphite components, then erosion resistance is improved, but coating integrity deteriorates due to CTE mismatch causing fracture under thermal stress
Solution Approach 1:
The interpenetrating phase composite structure provides erosion resistance through the hard SiC phase while maintaining coating integrity through the flexible graphite phase that accommodates thermal stress. The mutual interpenetration creates a structurally integrated system where neither phase can delaminate or fracture independently, as both form continuous networks that distribute stress throughout the structure.
Solution Approach 2:
The patent changes the structural parameters of the coating system by transitioning from a layered coating structure to an interpenetrating phase composite structure. This parameter change in the microstructure allows the material to maintain erosion resistance while accommodating thermal expansion differences, preventing fracture and delamination under thermal stress conditions.
3Ease of operation
If graphite is used for its advantageous properties, then electrical conductivity and machinability are maintained, but chemical resistance and particle generation resistance deteriorate
Solution Approach 1:
The interpenetrating phase composite maintains electrical conductivity through the continuous graphite phase while providing chemical resistance through the continuous SiC phase. The mutual interpenetration ensures both phases form percolating networks, allowing graphite to conduct electricity throughout the structure while SiC provides the chemical barrier properties that protect the graphite from oxidation and chemical attack.
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 composite exhibits improved thermal shock resistance, erosion resistance, and reduced particle generation, enabling longer component life and reduced maintenance costs in high-temperature applications, while maintaining electrical conductivity and mechanical integrity.
Implementation Method 1
contacting a graphite article with silicon monoxide (SiO) gas under chemical reaction conditions that are effective to convert an exterior portion of the graphite article to a silicon carbide matrix material
Data Source
AI summary
A silicon carbide-graphite composite is described, including (i) interior bulk graphite material and (ii) exterior silicon carbide matrix material, wherein the interior bulk graphite material and exterior silicon carbide matrix material inter-penetrate one another at an interfacial region therebetween, and wherein graphite is present in inclusions in the exterior silicon carbide matrix material. Such material may be formed by contacting a precursor graphite article with silicon monoxide (SiO) gas under chemical reaction conditions that are effective to convert an exterior portion of the precursor graphite article to a silicon carbide matrix material in which graphite is present in inclusions therein, and wherein the silicon carbide matrix material and interior bulk graphite material interpenetrate one another at an interfacial region therebetween. Such silicon carbide-graphite composite is usefully employed in applications such as implant hard masks in manufacturing solar cells or other optical, optoelectronic, photonic, semiconductor and microelectronic products, as well as in ion implantation system materials, components, and assemblies, such as beam line assemblies, beam steering lenses, ionization chamber liners, beam stops, and ion source chambers.