Crucible Isolating Layer Spraying Method
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Solution Overview
Problem
Current methods for forming an isolating layer on crucibles used in silicon ingot manufacturing are prone to cracking, leading to quality issues and reduced yield, and the service life of the crucibles is not adequately extended due to the damage caused by reaction with molten silicon.
Innovation Solution
A method involving uniform spraying of a slurry onto the inner surfaces of a crucible, using an optical positioner to align specific areas and an S-shaped movement with a spray gun, along with pre-spraying in the solid-liquid interface area to create a thickened isolating layer, which enhances the crucible's protection and extends its service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brushing method is used to form the isolating layer, then the isolating layer can be formed on the inner wall of the crucible, but the isolating layer is prone to cracking which reduces the quality and yield of silicon ingots
Solution Approach 1:
The patent replaces the mechanical brushing method with a spraying method to form the isolating layer. The spraying process uses a spray gun to atomize and deposit slurry uniformly onto the inner wall of the crucible, eliminating the mechanical contact and pressure that cause cracking in the brushing method. This substitution of mechanical action with aerosol deposition resolves the contradiction between forming an isolating layer and preventing cracks.
Solution Approach 2:
The patent changes the deposition parameters by controlling spray distance (20-30 cm), spray pressure (60-80 psi), and spray speed to achieve uniform coating thickness. These parameter optimizations ensure the isolating layer is deposited evenly without the defects associated with mechanical brushing, thereby improving both reliability and manufacturing precision.
2Reliability
If the brushing method is used to form the isolating layer, then the isolating layer can be applied to protect the crucible, but complicated steps are needed to ensure the coating layer is smooth
Solution Approach 1:
The spraying method replaces the complex multi-step brushing process with a single automated spraying operation. The spray gun can cover large areas uniformly in one pass, eliminating the need for multiple brushing steps, alignment adjustments, and manual interventions required to achieve smooth coating with the brushing method.
Solution Approach 2:
The spraying process is self-regulating through proper parameter control (pressure, distance, speed), allowing the system to automatically achieve uniform coating without complex manual adjustments or monitoring steps that are necessary in the brushing method.
3Reliability
If the brushing method is used to form the isolating layer, then the isolating layer can be formed on the inner wall, but abnormalities such as bristles and impurities need to be dealt with instantly during the process
Solution Approach 1:
The spraying method eliminates the physical presence of bristles that can break and contaminate the coating. The slurry is delivered through a nozzle as an aerosol, completely removing the source of bristle-related abnormalities and simplifying the operation by eliminating the need for instant troubleshooting of brush issues.
Solution Approach 2:
The patent introduces air or gas as an intermediary carrier to deliver the slurry from the spray gun to the crucible surface. This intermediary medium replaces the direct mechanical contact of brush bristles, preventing impurity introduction while maintaining effective coating application.
4Duration of action of stationary object
If the isolating layer is formed to protect the crucible from molten silicon reaction, then the service life of the crucible can be extended, but the current method produces cracking that reduces the effectiveness of protection
Solution Approach 1:
The spraying method creates a continuous, crack-free isolating layer that provides reliable protection against molten silicon reaction. By eliminating the mechanical pressing and brushing actions that cause micro-cracks, the sprayed coating maintains its integrity throughout the crucible's service life, ensuring consistent protection and extending usable duration.
Solution Approach 2:
The patent optimizes coating parameters including spray distance (20-30 cm), pressure (60-80 psi), and multiple coating passes to achieve uniform thickness and complete coverage. These parameter controls ensure the isolating layer is dense and free of defects, maximizing its protective function and extending crucible service life.
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 achieves a uniform and robust isolating layer that reduces the risk of adhesion and improves the quality and yield of silicon ingots by ensuring a consistent coating and increased crucible durability.
Implementation Method 1
a plurality of spraying processes are performed to form an isolating layer on the bottom surface and the wall surface of the round crucible
Data Source
AI summary
A method for forming an isolating layer of a crucible includes placing a round crucible sideways with a bottom surface of an inside thereof perpendicular to a horizontal plane, and then performing a plurality of spraying processes to form the isolating layer on the bottom surface and a wall surface of the round crucible. Each spraying process includes spraying a slurry on the bottom surface; using an optical positioner to set a spraying range the same as one of a plurality of partial areas divided from the wall surface; aligning one of the plurality of partial areas with the spraying range; fixing the round crucible and spraying the slurry in the spraying range; stopping the spraying; and rotating the round crucible to move another partial area to the spraying range. Then, the steps are repeated until the spraying of all the partial areas is completed.