Composite Laser Ceramic Polishing for Crack-Free Submicron Finish
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Solution Overview
Problem
Conventional ceramic polishing methods, including laser polishing, face challenges such as high thermal and mechanical stress, significant material removal, and difficulty in achieving submicron precision without damaging the surface geometry, especially for hard and brittle materials like alumina ceramics.
Innovation Solution
A composite asynchronous polishing method using a picosecond laser to generate micro-nanoparticles with high surface activity, followed by a nanosecond laser to melt these particles into a dense smooth layer, controlling the time interval between the two processes to minimize thermal impact and material removal, thereby achieving high-precision submicron polishing without surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional mechanical polishing method is used, then processing can be performed, but processing time is long and processing efficiency is low
Solution Approach 1:
The patent replaces conventional mechanical polishing methods with laser-based processing. Specifically, it uses a picosecond laser to generate micro-nanoparticles on the ceramic surface, followed by a nanosecond laser to melt and smooth these particles. This substitution of mechanical contact with optical fields eliminates friction and mechanical stress while achieving faster processing speeds and higher efficiency.
2Ease of manufacture
If conventional mechanical polishing method is used, then processing can be performed, but mechanical damage, subsurface crack and other defects are produced
Solution Approach 1:
The patent replaces mechanical contact polishing with a two-stage laser process. The picosecond laser ablates the surface to create micro-nanoparticles without mechanical pressure, and the nanosecond laser melts and smooths these particles. This optical-based approach completely eliminates mechanical damage, subsurface cracks, and compressive stress that are inherent in conventional mechanical polishing.
3Productivity
If medium and long pulse thermal polishing is used, then processing efficiency is high, but large heat-affected zone, thermal crack and ablation are produced
Solution Approach 1:
The patent fundamentally changes the temporal parameters of laser pulses. Instead of using medium and long pulse durations that cause excessive heating, it employs picosecond-scale pulses (extremely short duration) to ablate material with minimal heat diffusion. This is followed by nanosecond-scale pulses to melt and smooth the particles. The dramatic reduction in pulse duration prevents the formation of large heat-affected zones and thermal cracks while maintaining high processing efficiency.
4Manufacturing precision
If single ultra-fast laser polishing is used, then material micro-removal is achieved, but it is difficult to effectively repair original pores, cracks and other defects
Solution Approach 1:
The patent merges two distinct laser processes into a composite asynchronous polishing method. The first process (picosecond laser) removes material and creates micro-nanoparticles, while the second process (nanosecond laser) melts and smooths these particles to fill in pores and cracks. By combining material removal with material redistribution in a single integrated process, the method achieves both high surface precision and effective repair of subsurface defects.
5Manufacturing precision
If laser milling process is used, then surface roughness decreases with machining depth, but large milling depth is required and original surface morphology is completely changed
Solution Approach 1:
The patent applies partial action by using extremely low energy density in the nanosecond laser stage. Instead of removing large amounts of material through deep milling, it uses just enough energy to melt and smooth the micro-nanoparticles created by the picosecond laser. This partial action achieves the desired surface roughness reduction while requiring minimal material removal and preserving the original surface morphology, avoiding the excessive material removal and morphological changes associated with traditional laser milling.
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
This method effectively reduces surface roughness to submicron levels, eliminates micro-cracks and pores, and maintains the original surface morphology with minimal material removal, offering high precision and efficiency in ceramic polishing.
Implementation Method 1
a picosecond laser is used to scan and irradiate a ceramic surface along a scanning path; after irradiation with the picosecond laser, microscopic protrusions on the ceramic surface are removed to achieve a preliminary flattening, and micro-nanoparticles with high surface activity are generated
Implementation Method 2
low energy density nanosecond laser is used to irradiate and melt these micro-nanoparticles with high surface activity, which can easily form a dense and smooth fine crystal melting layer
Data Source
AI summary
The invention disclose a picosecond-nanosecond laser composite asynchronous ceramics polishing method. First, a picosecond laser is used to scan and irradiate the ceramic surface along the scanning path. At the same time, ceramic surface is initially flattened and the electronic state of materials is removed by picosecond laser to produce micro-nanoparticles. Micro-nanoparticles exist as ionized state in the adjacent space region of irradiated ceramics surface. Then, low energy density nanosecond laser is used according to a preset time to irradiate and melt these micro-nanoparticles which can easily form a dense and smooth fine crystal melting layer to achieve the polishing effect. The present disclosure fixes the generation of micro-cracks and pores in traditional laser polishing process. It overcomes the shortcomings of traditional laser polishing such as large thermal influence zone, easy to generate micro-cracks and pores on the surface, etc. High efficiency and high precision submicron level fine polishing with very low material removal amount is realized.