Mechanochemical Polishing of Advanced Ceramics

Mechanochemical polishing is one of the processing methods based on the principle of Dry media reaction polishing. Soft abrasive particles, together with appropriate polishing fluid, generate high temperature and high pressure due to friction at the contact point between the workpiece and abrasive particles. Dry media reaction occurs in a very short contact time, and the reactants are removed by friction to achieve the removal and polishing of nanometer sized micro units. The basic element of mechanochemical polishing is the use of soft fine abrasive particles that can Dry media reaction with the workpiece.

1. Processing characteristics

The results of processing sapphire with various particles based on mechanochemical Dry media reaction show that α- Comparison of processing rates of Fe3O4 and TiO2 particles α- The processing rate of Al2O3, FeAl2O4 particles and diamond micro powders is high. This indicates that using highly reactive particles has a higher machining efficiency than pure mechanical polishing, and diamond powder polishing is prone to damage on the surface of the workpiece.

If the goal of processing is to improve surface roughness and reduce processing deterioration layers, ultrafine powders should be used and processing pressure should be reduced. The processing efficiency increases with the increase of the polishing disc speed, and the processing pressure within the range of 60-180kPa will not have a negative impact on surface roughness.

After determining the material of the workpiece, select the substances that can react with the workpiece from the chemical phase diagram, and determine the powder based on its hardness and other physical properties. Do not choose powders with a high melting point. When selecting the material for polishing the disc, it is important to avoid complex reactions between powder and the surface of the disc. In principle, it is hoped that the disc and powder are of the same material. As long as the reaction is not disrupted, the processing atmosphere can be dry or wet.

2 Processing surface properties

In the mechanochemical polishing of functional crystal materials, attention should be paid to the residual reaction products in the processed metamorphic layer. If SiO2 particles (particle size 20nm) are used for wet floating polishing of sapphire on a moontin polishing disc, a machined surface with a surface roughness close to 1nm can be obtained. According to the Kikuchi line in the metamorphic layer image of the machining surface measured by Electron diffraction, it shows that the crystallization of the machining surface is basically free of distortion.

The results of surface ion microscopy polarization mirror (IMA) analysis and Auger (secondary spectroscopy) electron spectroscopy analysis show that there is almost no residue of SiO2 and its reaction products on the surface of sapphire.

The impact on the electromagnetic properties of Mn Zn ferrite: Diamond micro powder polishing has a deep processing modification layer, resulting in a low initial magnetic permeability. Mechanochemical polishing can obtain surface properties to the same extent as chemical corrosion. Due to the almost absence of processed metamorphic layers, high electromagnetic properties can be obtained.

3 Application of Mechanochemical Polishing

The examples listed above are all mechanical chemical polishing of sapphire as the object. Mechanochemical polishing can also process other crystal materials, such as crystals, silicon single crystals, and Mn-Zn ferrite. However, there are the following requirements for the powder used: the powder must be soft compared with the workpiece, and must be able to produce Dry media reaction with the workpiece. Therefore, suitable powders and processing conditions must be selected for each processing material.

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