Graphite Glass Molds with Titanium Carbide Coating
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Solution Overview
Problem
Graphite molds used in glass manufacturing are prone to oxidation and surface defects such as dimples and asperities, which are unsuitable for precision glass molding applications, and existing solutions like stainless steel molds are expensive and require extensive machining.
Innovation Solution
A precision glass mold with a fine-grained graphite body encapsulated by a vapor-deposited titanium carbide or titanium carbide and yttria coating, ensuring a coefficient of thermal expansion match with the graphite, preventing oxidation and providing a smooth, non-stick surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is used for glass molding, then the glass does not stick to the mold and the material is easy to machine, but the graphite is subject to oxidation at glass processing temperatures creating surface defects
Solution Approach 1:
The patent applies composite materials by combining graphite with a protective coating layer (such as boron nitride, silicon oxide, or metal alloys) to create a composite mold structure. The graphite provides the non-stick property and machinability, while the coating layer provides oxidation resistance at glass processing temperatures, thus resolving the contradiction between reliability and oxidation damage.
2Object-affected harmful factors
If stainless steel is used as mold substrate, then the mold is resistant to oxidation, but the mold requires extensive machining and surface finishing and is expensive to manufacture
Solution Approach 1:
The patent segments the mold into two functional parts: a graphite base material that is easy to machine and provides non-stick properties, and a separate protective coating layer that provides oxidation resistance. This segmentation allows each material to be optimized for its specific function without requiring extensive machining of the entire mold structure, thus reducing manufacturing complexity while maintaining oxidation resistance.
3Ease of manufacture
If graphite is used for precision glass molding, then the material is cost-effective, but the surface finish contains dimples and asperities that are unsuitable for precision applications
Solution Approach 1:
The patent uses composite materials by applying a smooth protective coating layer over the graphite surface. The graphite provides cost-effectiveness and ease of manufacture, while the coating layer (such as boron nitride or silicon oxide) provides a smooth surface finish suitable for precision glass molding applications, thus resolving the contradiction between cost-effectiveness and surface finish quality.
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 solution results in glass molds with reduced surface discontinuities, improved oxidation resistance, and cost-effective production, suitable for precision applications like consumer electronics and medical instruments, without the need for extensive machining.
Implementation Method 1
graphite is subject to oxidation at temperatures at which glass bending or other forming operations are conducted
Implementation Method 2
an encapsulating coating atop the graphite mold body and the one or more mold features. The encapsulating coating can comprise vapor deposited metal
Data Source
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AI summary
Precision glass molds are described, which are formed by coating a mold made from high purity, fine grain sized graphite, with a coating including titanium. In various implementations, the titanium coating is overcoated with yttria (Y203) to provide a high precision glass mold of superior performance character. The resultant glass molds can be used to form glass articles having a highly smooth finish, for high precision applications such as consumer electronic device applications, medical instruments, and optical devices. The use of high purity, fine grain size graphite allows molds to be machined at low cost, thereby eliminating the need to fabricate a metal mold that must be coated with multiple layers including metal diffusion barrier layers to meet operational requirements for such precision applications.