Abstract: A heat exchanger comprising: a heat exchange unit that exchanges heat between a heat transfer medium and a heat exchange object; a phase change unit, which comprises a liquid phase space that accommodates the heat transfer medium in a liquid phase state, and a gas phase space that accommodates the heat transfer medium in a gas phase state, the heat transfer medium being capable of moving into and out of the gas phase space; and a first channel along which the heat transfer medium is moved from the phase change unit to the heat exchange unit, wherein the heat exchanger is configured such that a saturated vapor pressure at a temperature of the heat transfer medium in the liquid phase flowing into the phase change unit differs from a pressure of the heat transfer medium in the gas phase in the gas phase space.

Abstract: Disclosed are a method for adjusting the pore size of a porous metal material and the pore structure of a porous metal material. The method comprises: permeating at least one element into the surface of the pores of the material to generate a permeated layer on the surface of the pores, so that the average pore size of the porous material is reduced to within a certain range, thus obtaining a pore structure of the porous metal material having the pores distributed on the surface of the material and the permeated layer provided on the surface of the pores.

Abstract: Before the end of the treatment of metal parts in a molten salt bath nitriding/nitrocarburizing station, a chamber, arranged so that the oxygen contained in the chamber can be discharged in order to create an inert atmosphere, is filled with a refrigerant in liquid form and with a strong capacity for volume expansion as it evaporates. All the parts treated are transferred into the chamber. The chamber is closed, and the parts are left in the chamber for a preset length of time to reach a temperature at which the salt congeals and forms a protective barrier. The parts are then removed and subjected to a rinsing operation.

Abstract: The present invention relates to a process for carburizing a metal article comprising: (1) heating the metal article to an elevated temperature, (2) coating the heated metal article with a graphite suspension to produce a graphite coated metal article, wherein the graphite suspension is comprised of graphite and an organic or inorganic liquid having a boiling point of at least 50° F. (28° C.) less than the elevated temperature to which the metal article is heated, (3) heat treating the graphite coated metal article under a non-oxidizing environment at a temperature which is sufficient to promote the diffusion of carbon into the metal structure of the article to produce a carburized metal article, and (4) cooling the carburized metal article to ambient temperature.

Abstract: A process for producing an ordered martensitic iron nitride powder that is suitable for use as a permanent magnetic material is provided. The process includes fabricating an iron alloy powder having a desired composition and uniformity; nitriding the iron alloy powder by contacting the material with a nitrogen source in a fluidized bed reactor to produce a nitride iron powder; transforming the nitride iron powder to a disordered martensitic phase; annealing the disordered martensitic phase to an ordered martensitic phase; and separating the ordered martensitic phase from the iron nitride powder to yield an ordered martensitic iron nitride powder.

Abstract: The invention relates to a method of gas carburizing a metallic article, where at least the surface region of the article consists of an alloy with a chromium content of at least 10 wt %. The carburizing is carried out by means of a gas containing carbon, which gas is heated to a temperature below approximately 5500C. The gas is an un-saturated hydrocarbon gas.

Abstract: The disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound. In particular, the disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound by reacting a green tubular structure made of a refractory metal with at least one reactive gas.

Abstract: The present nitriding-oxidizing method for a metal member is imposed, which includes providing a powdery nitriding agent comprised of a powdery nitride compound and inorganic powder, wherein the powdery nitride compound decomposes below a nitriding-oxidizing temperature to generate nitriding gas, and the inorganic powder does not react; embedding an essential part of the metal member to be nitrided and oxidized into the powdery nitriding agent, and then performing nitridization-oxidization while an oxygen-containing gas is always present in the powdery nitriding agent; and, if necessary, allowing the metal member after nitridization-oxidization to carry out a reoxidization in an oxygen-containing atmosphere. The method of the present invention has a broader temperature range for nitridization-oxidization.

Abstract: The present invention relates to a process for carburizing a metal article comprising: (1) heating the metal article to an elevated temperature, (2) coating the heated metal article with a graphite suspension to produce a graphite coated metal article, wherein the graphite suspension is comprised of graphite and an organic or inorganic liquid having a boiling point of at least 50° F. (28° C.) less than the elevated temperature to which the metal article is heated, (3) heat treating the graphite coated metal article under a non-oxidizing environment at a temperature which is sufficient to promote the diffusion of carbon into the metal structure of the article to produce a carburized metal article, and (4) cooling the carburized metal article to ambient temperature.

Abstract: The present invention relates to a method for modifying the surface of titanium or a titanium alloy by a fluidized bed carburization process. The surface hardness of the titanium or the titanium alloy could be improved by the fluidized bed carburization process. The above-mentioned method includes the following steps: providing a fluidized bed furnace, in which a carburizing agent containing charcoal and carbonate powders of which the weight ratio is 10˜8:0.5˜2 is used; placing titanium or a titanium alloy in the fluidized bed furnace at the temperature ranging from 900° C. to 1200° C. for carburizing the titanium metal or the titanium alloy for a period more than 3 minutes; and then taking the titanium metal or the titanium alloy out for quenching.

Abstract: The invention relates to a method of gas carburizing a metallic article, where at least the surface region of the article consists of an alloy with a chromium content of at least 10 wt %. The carburizing is carried out by means of a gas containing carbon, which gas is heated to a temperature below approximately 5500C. The gas is an un-saturated hydrocarbon gas.

Abstract: The present nitriding-oxidizing method for a metal member is imposed, which includes providing a powdery nitriding agent comprised of a powdery nitride compound and inorganic powder, wherein the powdery nitride compound decomposes below a nitriding-oxidizing temperature to generate nitriding gas, and the inorganic powder does not react; embedding an essential part of the metal member to be nitrided and oxidized into the powdery nitriding agent, and then performing nitridization-oxidization while an oxygen-containing gas is always present in the powdery nitriding agent; and, if necessary, allowing the metal member after nitridization-oxidization to carry out a reoxidization in an oxygen-containing atmosphere. The method of the present invention has a broader temperature range for nitridization-oxidization.

Abstract: The surfaces of a stainless steel part are made harder without sacrificing corrosion resistance by subjecting the part to low temperature carburization. The soot layer formed as a by-product of carburization is then removed without removing the non-coherent metal oxide layer which also forms as a by-product. A solid lubricant is then applied to reduce the coefficient of friction of the carburized surface. The by-product metal oxide layer acts as an anchor keeping the solid lubricant in place.

Abstract: An end product containing iron carbide (Fe3C) is produced from an intermediate product consisting of granular, directly reduced iron. Said intermediate product is supplied by an iron ore reduction plant and is fed to a carburization reactor. Liquid hydrocarbons are conveyed to the carburization reactor at temperatures of 500 to 900° C., at least part of the granular, directly reduced iron being subjected to a swirling movement. The end product removed from the carburization reactor consists of 5 to 90 wt. % Fe3C. A fluidization gas containing methane and hydrogen can be added to the carburization reactor in addition to the hydrocarbons.

Abstract: A method for heat-treating metallic workpieces, in which a flow of cooling gas is generated in a vacuum furnace by a fan in order to quench the workpieces, with the fan being driven by a rotary current motor that is operated with a predetermined supply voltage above a minimum pressure in the vacuum furnace which is determined with regard to the motor power of the rotary current motor. In order to additionally develop this method such that a simple and inexpensive improvement of the quenching effect is achieved, the fan is started at a pressure in the vacuum furnace which is lower than the minimum pressure, with the rotary current motor being operated with a second, lower supply voltage until the minimum pressure in the vacuum furnace is reached.

Abstract: The present invention features nitriding-treating the ferrous material to form a nitrided layer composed of at least one of iron nitride and iron carbide nitride on the surface thereof, and heating to maintain the ferrous material at a temperature of 500 to 700° C. in a treating agent (A), whereby chromium is diffused into the nitrided layer to form a compound layer composed of at least one of chromium nitride and chromium carbide nitride, wherein the treating agent (A) contains the following (a) as a main component and containing the following (b) and (c): (a) at least one of alkali metal chloride and alkaline earth metal chloride; (b) glass having silicone oxide as a main component; and (c) chromium.

Abstract: In order to produce a carbon solid solution or carbide-containing surface layer on a substrate, the substrate is immersed into a cold bath of liquid active medium, and heated inside the liquid active medium by heating means immersed in the liquid active medium as well.

Abstract: A nitride or carbonitride layer is formed on the surface of a metal material as follows: A treating agent composed of a refractory powder of alumina or the like and a powder of a metal for forming a nitride or a carbide or an alloy thereof is disposed in a fluidized bed furnace; the treating agent is fluidized to form a fluidized bed by introducing an inert gas; the fluidized bed furnace is heated to a temperature of not higher than 700.degree. C.; an activator of a halogenated ammonium salt is intermittently supplied into the fluidized bed at a rate of 0.001 to 5 wt %/hour based on the total amount of the treating agent; and the metal material to be treated is disposed in the fluidized bed during or after any of the above steps. For example, a nitride layer composed of only a metal for forming a nitride which contains almost no Fe--N is formed on the surface of iron steel even at a temperature as low as not higher than 700.degree. C.

Abstract: A process and apparatus for forming a hardened outer shell (40) on a refractory metal workpiece (36) preferably heated in a fluidized bed of metallic oxide particles (38) in an environment of an inert gas and a reactive gas with the reactive gas either oxygen or nitrogen. The workpieces (36) are heated in the fluidized bed to a temperature between 800.degree. F. and 1600.degree. F. for a period of over two hours to form hardened outer shell (40) in two layers (42, 44). Outer layer (42) is an oxide or nitride layer having a thickness (T1) between 10 microns and 25 microns. Inner layer (44) is a case hardened layer of the refractory metal having a thickness (T2) between 25 microns and 75 microns. In one embodiment (FIG. 3 ) workpieces (56) may be cold worked by peening from finely divided metal oxide particles (54) to provide a uniform surface texture for subsequent hardening.

Abstract: An endothermic gas generator having separate sources of oxygen and hydrocarbon gas at pressures above the pressure of the endothermic gas to be produced, the sources of oxygen and hydrocarbon gas being interconnected through separate pressure reducing valves and to a gas tight reaction chamber, the reaction chamber containing catalyst bodies and being heated to a temperature sufficient to support a reaction between carbon atoms and oxygen atoms to produce an endothermic gas, the reaction chamber having a outlet port for an endothermic gas resulting from the reaction of the oxygen and the hydrocarbon gases at a pressure approximately that of the mixture of gases entering the reaction chamber.