Method for Nitriding Titanium Alloy Surface by Glow Discharge Low Temperature Plasma Method

Abstract

The invention relates to a method for nitriding the surface of a titanium alloy by a glow discharge low-temperature plasma method, comprising the following steps: 1) TC4 titanium alloy substrate is ground, polished, alkali-washed, and pickled; 2) vacuum cleaning: suspending the substrate in a low-temperature glow In the vacuum chamber of the plasma nitriding equipment, vacuumize, control the flow of argon gas, and remove excess air; turn on the lighting, and further remove water vapor; vacuumize, heat and keep warm in the vacuum chamber, and further remove water vapor; into argon and nitrogen; pulse plasma cleaning; 3) nitriding; the method of the present invention is simple and easy, the required temperature is low and easy to control, and will not affect the structure and mechanical properties of the sample itself.

Description

technical field [0001] The invention belongs to the technical field of titanium alloy surface modification, and in particular relates to a method for nitriding the surface of TC4 titanium alloy (Ti-6Al-4V) by using a glow discharge low-temperature plasma method. Background technique [0002] Titanium alloys have the advantages of high specific strength, high plasticity and toughness, and good corrosion resistance, and are widely used in aerospace, petrochemical, mechanical construction, and biomedicine. For example, the application of titanium alloys in civil aircraft: About 11% of the titanium structure is used on the Boeing 777, and the meta-stable β titanium alloy Ti-10-2-3 with good malleability is used as the landing gear of the Boeing 777. Titanium 5896.7kg is used for the frame, and β-21S is resistant to corrosion of high temperature hydraulic oil, and is mainly used for the rear fairing. In addition, the supersonic civil aircraft is designed to cruise at Mach 2.14, ...

AI Technical Summary

Problems solved by technology

[0003] However, titanium alloys have poor wear resistance, and are prone to scratches and meshing when working under frictional conditions, and the surface hardness is not high. The hardness of pure titanium is about 150-200HV, and titanium alloys usually do not exceed 350HV. Such a hardness value is in many cases. Can not meet the requirements of actual production application

At present, in view of the shortcomings of low surface hardness, poor wear resistance and fatigue resistance of titanium alloys at home and abroad, surface modification technologies are mostly used, that is, chemical vapor deposition, physical vapor deposition, laser gas nitriding and other technologies are formed on the surface of titanium alloys. Nitride, carbide and boride modified layers to increase the surface hardness of titanium alloys, improve the wear resistance of titanium alloys, and expand the application range of titanium alloys

[0004] In surface modification technology, although a strengthening layer can be formed on the surface by deposition method, the bonding force between the strengthening layer and the surface of the substrate is poor.

The gas nitriding method is simple and easy, and the cost is low, but there are disadvantages such as high nitriding temperature, slow speed, thin and brittle permeated layer.

The ion implantation method uses high-energy ion implantation at room temperature or at a lower temperature to achieve surface modification. The film is well bonded to the substrate, and has strong resistance to mechanical and chemical effects. High processing temperature and long time, but also limited by the size and shape of the workpiece

The structure formed by the laser nitriding method is finer, and the nitriding layer can be closely combined with the surface of the substrate, but due to the rapid heating of the laser beam and the chilling effect of the substrate, the residual tensile stress is relatively large, and cracks are easily formed

Therefore, the existing laser gas nitriding on the surface of titanium alloy is not ideal enough to meet the engineering needs, and it is rarely used in actual production.