RU2192504C1 - Device for deposition of protective coatings on small-size articles - Google Patents

Abstract

FIELD: nonferrous metallurgy, particularly, formation of protective coatings; applicable in metal coating of parts produced either by metal working or by powder metallurgy. SUBSTANCE: device reactor is made in the form of two vertical parallel bodies of different diameters connected with each other in their upper and lower parts by adapters. Large diameter body has heater in its upper part, and its lower part is connected to adapter through truncated cone whose vertex facing downward and has liquid cooler. Small diameter body is made in the form of cylinder and is located outside of realm of heater and cooler. Mechanism of moving the parts to be treated is in the form of circular chain located on axles of parallel bodies. Secured to chain are horizontal plates. Chain drive system provides for chain motion upward in large-diameter body and return motion downward in body of small diameter. Branch pipes for introduction of reaction gas medium and withdrawal of reaction products are located in lower and upper adapters. Appliances for loading and unloading of treated parts are located above heater and in lower part of truncated cone. EFFECT: reduced irrational consumption of reagents, higher yield of metal to coating and excluded growing of scale on internal surface of reactor hot zone. 4 cl, 1 dwg

Description

 The invention relates to non-ferrous metallurgy, in particular to the formation of protective nickel coatings on small-sized products of various configurations during thermal decomposition of nickel tetracarbonyl vapor on the surface to be protected and can be used for parts obtained both by metal processing and powder metallurgy methods.

 A device for applying metal coatings on powder materials (A. S. USSR 494223 / Syrkin V.G., Welsh A.A., Prokhorov V.N., Silaev V.A.), which can be used for metallization of small-sized products . The device consists of a hollow drum - reactor with a removable cover for loading and unloading powder. The inner surface of the drum is made in the form of two truncated cones or ellipses, mated with bases. The inner surface of the lid is a segment. Along the axis of the drum is a tube equipped with a cooling jacket. On the bottom of the tube there are openings for introducing carbonyl vapor or carrier gas with carbonyl vapor. In addition, the tube is divided in length by a partition into two parts and is equipped with a vertical pipe for the removal of reaction products, as well as a pocket for a thermocouple. The drum is mounted on the tube using rolling bearings. The ends of the tube are mounted on fixed racks. The drum housing is mounted inside a split electric furnace having a separate rack. The rotation of the drum is carried out using an electric motor and gearbox.

 Due to the intensive mixing of the metallized particles during the rotation of the drum, a uniform coating is formed on all surfaces accessible to the gas. However, the presence of counter diffusion flows: carbonyl vapors to the substrate and reaction products from the substrate determines the low density of the resulting coatings. The adhesion of the resulting coatings to the substrate does not exceed 2 MPa.

 A device for applying protective coatings to small-sized products, containing a reactor with a lid, pipes for supplying gas and removal of reaction products, a heater and a liquid refrigerator.

The reactor is made in the form of a cylinder with a corrugated ruler located at its bottom along the generatrix. The heater and the liquid cooler, made in the form of a thermostatic casing, and nozzles are located at opposite ends of the cylinder. The cylinder has the ability to swing in a vertical plane. (RF patent 2072180 / Ermilov A.G., Rupasov S.I., Nesterov N.V.)
This device is a combination of similar features: a dual-zone reactor; the presence of a device for the directional movement of parts; the location of the gas inlet and outlet of the reaction products, taken as a prototype.

 A feature of this device is the directed movement of metallized products from the cold zone of the reactor, where carbonyl is adsorbed on the metallized surface, to the hot zone where the pre-adsorbed carbonyl decomposes only on the substrate with the formation of a dense coating. The disadvantage of this device is the possibility of a breakthrough of carbonyl vapor along the upper generatrix of the reactor during the pouring of the product layer during the pumping of the reactor. The result of this is not only a reduced yield of metal in the coating, but also the danger of metallization of the inner surface of the hot zone of the reactor.

 The objective of the invention is to provide a device that eliminates the breakthrough of carbonyl vapor through a layer of metallized parts from the cold zone of the reactor to the hot one, with the technical result of reducing the irrational use of reagents, increasing the yield of metal in the coating, and eliminating the increase of the skull on the inner surface of the hot zone of the reactor.

 The problem is solved in that in a device for applying protective coatings to small-sized products, including a two-zone reactor with a refrigerator and a heater, a mechanism for moving parts, pipes for supplying a reaction gas medium and removal of reaction products, devices for loading and unloading parts, according to the invention, vertically arranged the reactor is made in the form of two parallel shells of different diameters connected to the upper and lower parts by adapters, the larger diameter shell has in the upper part a heater, and the lower part is connected to the adapter through a truncated cone, with its top pointing down, and has a refrigerator, a case of a smaller diameter is made in the form of a cylinder and is located outside the dimensions of the heating device and the refrigerator; the mechanism for moving parts is made in the form of an annular chain with horizontal plates fixed to it and located along the axes of parallel housings, and a chain drive system that provides its upward movement in the case of a larger diameter and return movement downward in the case of a smaller diameter; nozzles for inputting the reaction medium and removal of reaction products are located in the lower and upper adapters, respectively; devices for loading and unloading parts are located above the upper cut of the heater and in the lower part of the truncated cone, respectively.

 The drawing shows a diagram of the proposed device.

 Cases 1 and 2 are connected in the upper and lower parts by adapters 3 and 4. The housing 1 is equipped with a heater 5 in the upper part and a cone 6 with a refrigerator 7 in the lower. A fixture 8 is provided for loading metallized parts, and a nozzle 9 is provided for unloading. A nozzle 10 is provided for supplying the reacting gas, and a nozzle 11 is provided for withdrawing reaction products. The mechanism for moving the parts consists of a continuous chain 12 with cymbals 13 mounted on it and a chain drive system 14 located in adapters 3 and 4.

 The device operates as follows. Metallized parts are loaded into the housing 1 through the loading device 8. To reduce the resistance of the layer of parts, loading is performed with periodic or continuous movement of chain 12. The number of parts to be loaded is determined by the height of the layer, the top level of which should not be lower than the upper cut of the heater by more than one third of the height of heater 5. After loading, the reactor is sealed and filled with gaseous carbon monoxide . Using a heater 5, the upper part of the layer is maintained at a temperature above the decomposition temperature of carbonyl, and in the lower part of the layer, the temperature of carbonyl sorption, which is determined by the temperature of the liquid in the liquid cooler 7. Chain 12 is driven by a drive 14 in the large-diameter case up and the small diameter down. The plates 13, mounted on a chain pick up the parts and move them in the center of the large case up from the lower cold zone to the upper hot one. The cone 6 serves to supply the coated parts to the plates 13. The reverse movement of the parts from the hot zone to the cold is carried out spontaneously under the action of gravity along the walls of a large case. This ensures thermal cycling of parts from the temperature of sorption of carbonyl on a metallized surface to the temperature of its decomposition. Through the pipe 10, a reaction mixture consisting of carbon monoxide and carbonyl vapor is fed. In the cold zone, carbonyl vapors are sorbed on the surface of the parts. When the chain 12 moves up, the plates 13 pick up parts with carbonyl adsorbed on their surface and transport them to the upper hot zone of the reactor, where the adsorbed carbonyl decomposes under the influence of temperature to form a dense coating and reaction products that are removed through the pipe 11. After the carbonyl decays, the parts return to cold zone of the reactor along the walls of a large vessel. The cycle repeats. The return movement of the circuit is carried out along the case of small diameter 2. To prevent spillage of parts into the lower adapter 4, a gateway 15 is provided. To prevent the plates from being carried out into the upper adapter, the plates are conical. The thickness of the coating layer is determined by the duration of the process. The return movement of parts along the walls of the reactor and the trays in the small-diameter case 2, directed against the movement of the gas stream, prevents the penetration of unsorbed carbonyl vapor into the hot zone and its decomposition on the walls of the reactor.

 The unloading of metallized parts is carried out through the device 9 with the continuous movement of the chain 13.

 The gateway 15 and the upper part of the housing of small diameter are made with entry cones. To prevent the breakthrough of gases into the environment, the reactor is sealed, and the rotation of the actuator 14 is carried out through the gland seal.

 For ease of installation and maintenance of the drive 14, the adapters 3 and 4 are made detachable.

 To reduce the resistance of the layer to the movement of the chain with the plates, a large-diameter case can be made in the form of a truncated cone, with its vertex facing down.

 The proposed design of the device provides the formation of a protective coating only on metallized products and eliminates the formation of coatings on the inner surface of the hot zone of the reactor and on the surface of the chain.

 The technical result is the reduction of waste of reagents; increasing the yield of metal in the coating and eliminating the buildup of the skull on the inner surface of the reactor hot zone.

Claims (4)

 1. A device for applying protective coatings on small-sized products, including a two-zone reactor with a refrigerator and a heater, a mechanism for moving parts, pipes for supplying a reaction gas medium and removal of reaction products, devices for loading and unloading parts, characterized in that the reactor is made in the form of two vertically arranged parallel housings of different diameters, connected in the upper and lower parts by adapters, a larger diameter case has a heater in the upper part, and the lower part It is equipped with an adapter through a truncated cone, with its apex facing down, and has a refrigerator, a case of a smaller diameter is made in the form of a cylinder and is located outside the dimensions of the heater and the refrigerator, the mechanism for moving parts is made in the form of a ring chain with horizontal plates fixed to it, located along the axes of parallel cases , and a chain drive system for moving it up in the case of a larger diameter and returning downward in the case of a smaller diameter, nozzles for introducing the reaction gas and removing the reaction products located in the lower and upper adapters respectively, means for loading and unloading the parts located above the upper edge of the heater and the bottom of a truncated cone, respectively.  2. The device according to p. 1, characterized in that the chain plates are made conical, the cone is directed upward.  3. The device according to p. 1 or 2, characterized in that the reactor adapters are made detachable.  4. The device according to claim 1 or 3, characterized in that the case of a larger diameter is made in the form of a truncated cone, facing downward.