Method for mfg. large hole diamond coating drawing die

Abstract

A process for preparing big-aperture draw die with plated diamond layer includes choosing the drawing hard alloy die as substrate with aperture greater than 15 mm, corroding the hole surface by diluted hydrochloric acid and H2O2, washing, and depositing diamond layer and nano diamond layer on the hole surface in a reaction chamber by electrothermal wire CVD method. In said CVD method, an electrothermal wire assembly composed of more electrothermal wires are used. Its advantages are high thickness and quality of plated layer, low friction coefficient and long service life.

Description

Technical field: [0001] The invention relates to a method for preparing a large-aperture diamond coating drawing die, which is a new method for preparing a diamond coating, relates to a chemical vapor deposition (CVD) diamond coating drawing die preparation technology, and belongs to metallurgical metals Material plating technology field. Background technique: [0002] Various large-aperture drawing dies are widely used in metal drawing, stranding and pressing of multi-strand wires, thinning of metal pipe walls, pipe wall butt welding, sizing and other purposes. This type of mold is made of cemented carbide in most occasions. In some special occasions (such as aluminum-plastic or other metal and plastic composite pipe production), fluoroplastics are used to reduce the coefficient of friction. Because the wear resistance of cemented carbide is not as good as diamond, and when there is no lubricant, the coefficient of friction with some metals (such as aluminum) is relatively large...

AI Technical Summary

Problems solved by technology

However, due to the use of a single straight-drawing hot wire, when the hole diameter of the drawing die is large (> φ12 mm), the quality and deposition rate of the diamond deposited on the surface of the inner hole begin to decline significantly, further increasing the hole diameter > φ15 mm, The thickness, quality and coating adhesion of the coating will not meet the requirements of actual use

This is because, with the expansion of the pore diameter, the distance between the hot wire and the surface of the inner hole increases, and the probability of recombination of the dissociated active hydrogen atoms near the outer surface of the hot wire will greatly increase during the diffusion process to the inner hole surface, thus achieving The active hydrogen atoms on the surface of the inner pores will be greatly reduced, resulting in a decrease in the quality and growth rate of the diamond coating

In addition, since the surface of the inner hole is far away from the hot wire, its surface temperature drops, which also leads to a decrease in coating quality and growth rate

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