Procedure for plasma boriding

FIELD: metallurgy.

SUBSTANCE: procedure for plasma boriding metal surface out of titanium, of ally on base of titanium, of steel or of ferrochromium consists in introducing KBH4 into reaction chamber, where H corresponds to halogen. KBH4 is heated to temperature sufficient for release of BH3. BH3 is subjected to plasma discharge. There are generated activated boron containing particles diffused in metal surface. In an alternative procedure of the invention KBH4 is thermally decomposed producing KH and BH3. BH3 is directed to plasma formed with inert gas. Also, composition and conditions of plasma generation are selected to facilitate decomposition of BH3 into BH2+ and H. BH2+ is diffused into metal surface.

EFFECT: wear resistant metal surface produced without change of volume of substrate at boriding and with reduced consumption of poisonous chemicals.

13 cl, 1ex

 

The technical FIELD TO WHICH the INVENTION RELATES.

The present invention relates to a method of producing wear-resistant metal surfaces.

The prior art TO WHICH the INVENTION RELATES.

Borisovna known to increase the wear resistance of metal surfaces. Known various methods of Borisovna metal surfaces. Such methods create a boron layer on the metal surface. Typically these methods use a reactive boron compounds which penetrate the metal surface. Such reactive compounds include boron gaseous DIBORANE and trihalogen boron, including BCl3and BF3.

One way of Borisovna metal surfaces is a way to "solid fill". In these methods, the source of boron is in the form of solid powder, pastes or granules. The metal surface is filled with a solid boron source and then heated to release and transfer boron particles in a metal surface. This method has many disadvantages, including the necessity of using a huge excess boron source, leading to excessive formation of toxic wastes.

Another way of Borisovna metal surfaces uses a plasma charge for sposobstvo is of the migration of boron to the metal surface. Typically, the methods of plasma Borisovna used DIBORANE, BCl3or BF3where plasma charge reported gaseous boron reagent to release reactive boron particles. See, for example, the U.S. patents 6306225 and 6783794. However, these methods use corrosive corrosive and highly toxic gases, and thus difficult to implement on an industrial scale.

The processes of plasma Borisovna have a number of advantages, including speed and localized heating of the substrate. This prevents the change in the volume of metal in Borisovna piece due to annealing and controlled additional heat treatment to restore the original microstructure and crystal structure. In the result, it is desirable to have a process plasma Borisovna, which retains the advantages of plasma processing, at the same time reducing risk and costs associated with poisonous chemicals.

DETAILED DESCRIPTION of SOME embodiments

The present invention provides a method of Borisovna metal surface. According to the methods of the present invention KVH4in which X represents halogen, presented as a source of boron. The use of KVH4this has the advantage that it is a solid substance that is legados is available and easy to handle. In some embodiments, the implementation of KVH4is deposited in solid form in the presence of boeremag metal surface. Heat is supplied so that KVH4highlights gaseous BX3to which is supplied a plasma charge. Without going into any specific theory, it appears that plasma charge is the result of the formation of one or more active boron particles, which penetrate the metal surface. As used here, the term "activated boron particles" refers to any one or more boron-containing particles generated by the application of the plasma charge to the gas formed by heating KWH4. In some variants, one or more activated boron-containing particles include, but are not limited to such, In+, I+, I2+and I3+.

Used in the description of the term "Borisovna" refers to the process of introducing a boron-containing layer into the metallic surface.

As used here, the term "plasma" refers to ionized gas, and the term "plasma charge" refers to electric current, supplied to the gas for plasma formation. In some embodiments, the implementation of the plasma according to the present invention includes one or more activated boron hour is CI, including but not limited to those, In+, I+, I2+and I3+in which each X is a halogen.

As used here, the term "glow discharge" refers to the type of plasma formed by passing current with a voltage of 100 V to several kV through gas. In some embodiments, the implementation of the gas is argon or another noble gas.

In some versions, each X represents a chlorine, KBX4represents KBCl4.

In other embodiments, the implementation of each X represents fluorine, KBX4represents KBF4.

In some designs, the present invention provides a method of Borisovna metal surface, comprising the stage of:

(a) introducing KVH4in which each X is a halogen;

(b) heating KWH4at a temperature sufficient to release the I3; and

(C) the application of the plasma charge to the I3to create one or more activated boron particles for diffusion into the metal surface.

In other versions of the present invention is a method of Borisovna metal surface, comprising the stage of:

(a) introducing KVH4in which each X presented yet a halogen, in the presence of the metal surface;

(b) heating KWH4at a temperature sufficient to release the I3; and

(C) the application of the plasma charge to the I3to create one or more activated boron particles for diffusion into the metal surface.

In some versions boerema metal surface is a ferrous metal. Ferrous metals are well known to the specialist in the art and include steel, ferrochrome with a high content of chromium and titanium alloys. In some embodiments, the implementation of the ferrous metal is a stainless steel or 4140 steel. In other versions of the stainless steel shall be elected from steel grades 304, 316, 316L. According to one variant of implementation of the ferrous metal is a steel selected from grades 301, 301L, A, 1080 or 8620. In other versions of boerema metal surface is a titanium or titanium containing metal. Such such metals include titanium alloys.

In other embodiments, the implementation of KVH4is introduced in solid form into the chamber containing boeremag metal surface. KVH4is heated to release the I3. Plasma charge is attached the opposite side of the chamber to create a plasma, comprising one or more activated boron particles. The temperature at which KVH4heated, is sufficient to discharge from it I3. In some versions KVH4heated at a temperature of from 700 to 900°C.

The number of KVH4used in the methods according to the present invention, it is sufficient to maintain a pressure from about 10 to about 1500 PA inside the reaction chamber. In some versions the pressure is from about 50 to about 1000 PA. In other embodiments, implementation of the pressure is from about 100 to about 750 PA. Specialist-technologist will be clear that thermal decomposition KVH4with the formation of I3has the result of increasing the pressure inside the reaction chamber. Without going into any specific theory, it appears that the number of moles formed gaseous BX3can be calculated by measuring the pressure rise.

In some embodiments, the implementation of the hydrogen gas is introduced into the chamber with KVH4and obtained from thermal decomposition of I3. Without going into any specific theory, it appears that elemental hydrogen facilitates the decomposition of I3one or more activated boron particles when exposed to plasmin is on charge. In some versions of gaseous hydrogen is introduced in an amount which is equal to the number of redundant I3or is the molar excess compared to the last.

In some embodiments, the implementation of the gaseous BX3and optional hydrogen are introduced into the plasma stream of inert gas, for example argon. Plasma can accelerate the diffusion of the reactive elements and provide high-speed impact of a reactive boron particles on the treated metal surface. In some versions plasma is a plasma glow discharge. The substrate can be any material that is suitable for use in the methods of plasma processing, such as steel or titanium alloys. KVH4may be subjected to decomposition in a separate chamber for the decomposition connected with a plasma chamber, or as decomposition and plasma processing can occur in separate zones of a single reaction vessel.

As described here, the methods according to the present invention include the stage of application of the plasma charge to create one or more activated boron particles. In some embodiments, the implementation of the plasma charge is a pulsed plasma charge. In other embodiments, and the implement attached plasma charge in which the voltage is adjustable from about 0 to about 800 C. In still other embodiments, the implementation of the current is about 200 And the maximum.

Other variants of the invention will be apparent to the specialist-technologist from consideration of the description or the practice of the disclosed invention here. It is assumed that the description and examples be considered only as illustrative, with the true scope and meaning of the invention indicated by the following claims.

EXAMPLE

Steel item is placed in the reaction chamber together with 50 g KBF4in the crucible of boron nitride. Reaction chamber vacuumized to a pressure of 0.01 PA. The crucible is heated to a temperature of 900°C, leading to the decomposition of KBF4with the formation BF3. A gas mixture of H2/Ar with 10%hydrogen is added to the reaction chamber to a pressure of 500 PA. The electric discharge is attached at a voltage of 600 V and current of 150 A. the Reaction is continued for about 3 hours or until until you achieve the desired introduction of boron.

1. How Borisovna metal surface of the titanium alloy based on titanium, steel or ferrochromium, including introduction to the reaction chamber KVH4in which X represents halogen, heating KVH4at a temperature sufficient to highlight the I3and the application of the plasma discharge to the I 3to create the activated boron particles for diffusion into the metal surface.

2. The method according to claim 1, in which KVH4injected into the reaction chamber containing the metal boeremag surface.

3. The method according to claim 1, in which the activated boron-containing particles are selected from The+, I+, I2+or I3+.

4. The method according to claim 3, in which plasma discharge is a plasma glow discharge.

5. The method according to claim 1, in which KVH4heated at a temperature of from 700 to 900°C.

6. The method according to claim 1, in which additionally at the camera with KVH4introducing hydrogen gas.

7. The method according to claim 6, in which gaseous hydrogen is introduced into the argon flow.

8. Method of plasma Borisovna metal surface of the titanium alloy based on titanium, steel or ferrochromium, including introduction to the reaction chamber KVH4in which X represents halogen, thermal decomposition KVH4with the formation of the HH and I3the direction of I3in the plasma is generated with an inert gas, and the composition and conditions of formation of plasma pick up so that I3decomposes at I2+and X-and by the diffusion of I2+in the metal surface.

9. The method according to claim 8, in which X represents the t of a fluoride.

10. The method according to claim 8, in which X represents chlorine.

11. The method according to claim 8, in which X represents bromine.

12. The method according to claim 8, in which additionally at the camera with KVH4introducing hydrogen gas.

13. The method according to item 12, in which gaseous hydrogen is introduced into the argon flow.



 

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