TW208721B - - Google Patents

Abstract

An economical method for applying nitride layers to titanium and titanium alloys. In a short time, layer thicknesses of 20 mu m are achieved by nitriding under pressure in an ammonia atmosphere. Temperatures of 500 to 1000 DEG C and pressures of 0.2 to 10 Mpa are required for this purpose.

Description

A6 B6 2087 ^ 1 V. Description of the invention (1) The present invention relates to a method for covering the parts composed of titanium and titanium alloys with nitrides. This method generally makes the parts under pressure and above 500. At a temperature of ° C, it is subjected to thermochemical treatment of ammonia or a gas mixture containing ammonia. Titanium has some advantages over steel as a building material, that is, it has a low specific gravity, corrosion resistance and high strength. On the other hand, its hardness is quite low, and surface treatment is required to increase its wear resistance. This surface treatment usually involves the generation of a titanium master and a titanium nitride layer. The methods known to date for nitriding parts composed of titanium and titanium alloys include the use of high-energy gases or electromagnetic fields. These methods are very expensive and can only be applied to parts with a simple geometric construction. In DE-PS 17 96 212, it is mentioned that at a relatively high temperature and normal pressure, the purpose of hardening titanium is achieved by forming a nitride layer in an ammonia gas enclosure. Although this is done to create a fairly thick and hard layer, this method has no practical value because the hydrogen diffusion involved can make the core of the component brittle. EP — OS 0 105 835 describes a method for forming a nitride layer on a component composed of titanium and a titanium alloy, its exposing the component in an autoclave to a pressure of at least 1 OMP a and a temperature of at least 2 〇〇 ° C, and in the ammonia gas. In this case, the ammonia must be very pure. Preferably, nitridation occurs at a temperature of 9 0 ~ 1 3 OMPa and 9 3 0 ° ~ 1 0 0 0 ° C. This method has the disadvantage that it is extremely expensive due to the use of autoclaves and extremely pure ammonia, and that a 20 urn thick layer can only be prepared within a period of 3 or more hours. Therefore, the goal of the present invention is to develop a method to cover the nitride layer with ί, please read the precautions on the back before filling in this page). Install · • Green · A 4 (210X297 佂 没) -3-08 'like A6 B6 5. Description of the invention (2) (please read the notes on the back and then fill in this page) On the parts composed of titanium and titanium alloys, it is common to use ammonia or ammonia-containing gas mixtures for thermochemical treatment of the parts. Under a pressure and at a temperature higher than 500 ° C, this method is very economical, and enables a nitride layer to be formed in a relatively short time, with a thickness of 20 urn or more. According to the present invention, this goal can be achieved by processing at a temperature of 500 to 100 ° C. and a pressure of 0.2 to 10 M Pa. 2MPa。 Wherein the partial pressure of ammonia must be at least 0. 2MPa. It has been proved that the temperature of 7 0 0- 9 5 0 ° €: the temperature and the pressure of 0.5-71 ^? &Amp; have special advantages, among which the partial pressure of ammonia must also be at least 0.2 Mpa.

Through this pressurization method, components made of titanium and titanium alloys, regardless of their shape and size, can become a nitride layer with a thickness of 20 or more in a box furnace, which is already sufficiently thick. Surprisingly, no extra pure gas is needed, as long as normal commercial quality ammonia is sufficient. In addition, nitrogen and ammonia can be mixed, so that only a partial pressure of ammonia of at least 0.2 MP a is required during the nitriding process. Over a wide range of pressures, the thickness of a titanium nitride layer formed depends on temperature and processing time. The surface layer is golden, and there is a significant increase. When the pressure is in the range above 6MP a, the thickness of the layer is almost independent of the pressure. The figure below shows the formation of a titanium nitride layer on a part composed of pure titanium, commonly a function of pressure and temperature in an ammonia-containing air mass. Even at a temperature of 500 ° C, such as an absolute pressure of 2 MPa (= 20 bar), a 1 μm thick TiN layer 4 (210X297 male) can be measured after 1 hour -4-Α6 ____ Β6 V. Description of the invention (3) ◊ At 8 8 0 ° C, this example can form a pure T i Ν layer with a thickness of 20 um. When the pressure is 6 MPa (= 60 bar), it forms a τ i Ν of 3 0ttm Layer, this pseudo example is formed when the sample is kept at 880 ° C for 1 hour. When the pressure is increased to 9MPa (= 90 bar), the effect of pressure on the thickness of the TiN layer will be reduced. This increase is no longer linear. Even if the pressure is higher, due to the rapid formation of the tight TiN layer, only the diffusion of nitrogen through the layer is a time-dependent factor. In the same way as pure titanium, for example Ti alloy A6 6V4 can also be nitrided. No autoclaves are required for these overlays, but they can be processed in standard commercial box furnaces. Please read the precautions on the back of KI before filling out this page) • Install · • Line · Armor 4 (210X297 Public Issue) -5 *

Claims (1)

A7 B7 C7 D7 (A) VI. China Interview Patent Scope 81 r 〇81 B 1 Annex II: & Patent Application No. 79109059 Chinese Application Patent Scope Amendment February 2002 Amendment 1. A method for The nitride layer is covered on the part composed of titanium and titanium alloy. This method is to subject the part to thermochemical treatment of ammonia or an ammonia-containing gas mixture under pressure and a temperature higher than 5001. The treatment is carried out at a temperature of 500 ~ 1000, and a pressure of 0.2 ~ 10 MPa, and the partial pressure of ammonia must be at least 0.2 MPa Pa2. It is characterized in that the processing is carried out at a temperature of 7 0 ◦ ~ 9 5 0 * 0 and a pressure of 0.5 ~ 7 μ pa, and the partial pressure of ammonia must be at least 0.2N1Pa (please first «! Read the back Please pay attention to this page and then fill out this page). ¾. Printed by the Beigong Xiaozhi Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs "» Standards Applicable to B Η Family Standards (CNS) T4 Specification (210x297)