Study On Preparation And Technology Of Diamond Coating For Wire Drawing Die Based On Gas Circulation

Wire drawing die is a key part of metal drawing and processing.CVD diamond has high hardness and good wear resistance.Depositing CVD diamond coating on the surface of the inner hole of the mold can improve the life and quality of the drawing die significantly.A large amount of reactive gas is wasted during traditional HFCVD diamond film deposition,and the rate of diamond coating deposition is slow.This paper aims to reduce production costs and improve production efficiency.Design gas circulation system for traditional equipment and verify the feasibility of the improvement scheme through simulation and experiments,then explore the small batch production under gas circulation conditions.In the final ? optimized the process route of drawing die polishing,provided a complete processing solution for the production of wire drawing die diamond coating.The main content and results of this paper are as follows:(1)First ? modified the traditional HFCVD deposition equipment and designed the gas circulation system.Then ? selected suitable gas circuit components,improved the platform structure of the reaction chamber.Last ? proposed a calculation method of the carbon source gas replenishment in circulating gas circuit,in the final ? transformed the original equipment successfully.(2)Establish different structural models of wire drawing die when deposited diamond.By comparing the gas flow field distribution in the vicinity of drawing die of conventional structure and improved gas circulation structure,it is proved that the structure of openings on the platform and double air inlet can effectively improve the flow rate and uniformity when gas flow through the holes in the wire drawing die,then discussed the effects of different process parameters(air inlet speed V_in,air inlet height H_in and mold distance L)on the flow field distribution of batch deposition experiments.(3)Use the optimized parameters obtained by simulation to guide the experiment.The feasibility of calculating the carbon source gas replenishment by weighing method was verified by comparative experiments.Analyze the coatings in the five areas of the inner hole and the good coating quality verifies the rationality of the simulation optimization.Explore the growth rate of diamond film in the gas process by comparative experiments.The results show that the deposition rate of the improved equipment is greatly increased.The longer the deposition time,the faster the growth rate.(4)Use the consolidated abrasive line polishing technology to polish the wire drawing die which was produced by the gas circulation process.For diamond coatings with an average thickness of 20?m,first use 800#diamond wire for 0.5h rough polishing,and then use 1600#diamond wire for 1.5h fine polishing to obtain a diamond film with a surface roughness of 0.092?m finally.