CN103314132A

CN103314132A - Surface treatment of metal objects

Info

Publication number: CN103314132A
Application number: CN2011800646371A
Authority: CN
Inventors: 丹尼尔·法比加尼克
Original assignee: Hard Technologies Pty Ltd
Current assignee: Hard Technologies Pty Ltd
Priority date: 2010-11-17
Filing date: 2011-11-17
Publication date: 2013-09-18
Anticipated expiration: 2031-11-17
Also published as: CN103314132B; US20130299047A1; JP2014504329A; WO2012065220A1; JP5951623B2; EP2640867A1; AU2011331909A1; AU2011331909B2

Abstract

The specification discloses a process for forming a diffusion surface layer extending inwardly from an outer surface of a metal substrate or member to be treated. The process includes in a first activation stage, providing an activation treatment furnace containing an inert particulate refractory material and a metal based material including metals and metal halides for forming said diffusion surface layer, the activation treatment furnace having a flow of an inert gas and a flow of an hydrogen halide gas introduced into the inert particulate refractory material and the metal based material in the activation treatment furnace for a first period of time to activate at least an outer surface region of said metal based material to form an activated metal based material; and in a subsequent diffusion stage, providing a diffusion treatment furnace and introducing said metal substrate into said diffusion treatment furnace, said metal substrate having been pretreated to form a diffusion zone extending inwardly from the outer surface of the metal substrate in which nitrogen has been diffused to form an inner diffusion zone and an outer compound or white layer formed, at least in part, by an iron nitride, an iron carbide or an iron carbonitride compound without an oxide layer on said outer surface of the metal substrate, treating the metal substrate in the diffusion treatment furnace, sealed against the ingress of atmospheric air and under an inert gas atmosphere, in the absence of hydrogen halide gas for at least a second period of time, in the presence of said activated metal based material, to form said diffusion surface layer on said metal substrate.

Description

The surface treatment of metal object

The present invention relates to for the treatment of metal base to obtain the method and apparatus of diffusing surface layer at described base material.

Traditionally, metal finishing is included in and forms nitrided surface on the base material, then the coating of physical vapor deposition such as titanium, chromium nitride or with the carbon carbonitriding on described surface as adhering coating.Carry out a few thing, in its described work, surfacing material has been diffused in the surface region of base material in surface diffusion at nitrogen, made chromium or titanium nitride or nitrogenize carbon-coating on described surface.European patent number 0471276,0252480,0303191 and the patent specification of having delivered of international publication number WO/47794 such treatment process is disclosed.Such method can provide performance better surface treatment, this is owing to described upper layer is that diffusion layer is not only the coating that is attached to base material, yet, for obtaining this required result to required material and the working control of parameter, be proved to be very difficult.With for example for example use of HCl of halide gas that mixes of hydrogen and/or ammonia of reactant gas or inflammable gas, in the structure of mixed gas group, cause difficulty.In addition, HCl and other halide gas are relatively costly, and a large amount of uses of such gas can bring the relatively costly processing of required product.In addition, halide gas can be at low temperatures forms solid ammonium chloride with the ammonia instantaneous reaction, its may barrier gas pipeline and even drain back in the magnetic valve and rate of flow meter of gas transportation facilities, cause obstruction and the latent lesion of equipment.

International patent application no PCT/AU2006/001031 discloses treatment process and the treatment unit that can form required diffusion layer at the metal base product, described method discloses in whole very long processing period and has supplied halide gas, although and the work of method is satisfactory, but because the required volume of halide gas that uses, tooling cost is very expensive.

Therefore, the purpose of this invention is to provide to form the diffusing surface layer than the more economical mode of art methods at metal base, still keep the reliable and safe method for processing of described metal base simultaneously.

Therefore, first aspect the invention provides the method for the diffusing surface layer that formation extends internally from the outside surface of metal base, and described method comprises:

(i) in activation stage, the activation treatment stove that contains the inert particle refractory materials and be used to form the metal_based material of described diffusing surface layer is provided, described activation treatment stove and accessory has in the inert particle refractory materials that is directed in the described activation treatment stove and the metal_based material and continues the inert gas flow of very first time section, in the presence of hydrogen halide, to handle the exterior surface area of described metal_based material, form the metal_based material of the activation of the surf zone with activation; And

(ii) in diffusion phase, the DIFFUSION TREATMENT stove is provided and described metal base is imported in the described DIFFUSION TREATMENT stove, described metal base is pretreated to form the spreading area that extends internally from the outside surface of metal base, nitrogen has been spread to form internal divergence district and at least part of by nitrided iron in described metal base, externalizing compound layer or the white layer of iron carbide or carbon nitrided iron compound formation, described outside surface at metal base does not have oxide skin, and in the presence of the metal_based material of described activation, sealed in case in the DIFFUSION TREATMENT stove of stop ring border air admission, under inert gas atmosphere, under the situation that does not have hydrogen halide, metal base was handled at least the second time period, to form described diffusing surface layer at described metal base.

Be that aforesaid method can also comprise easily:

(i) in pretreatment stage, form the described spreading area that extends internally from the surface of metal base, nitrogen has been spread to form externalizing compound layer or the white layer of internal divergence district and nitrided iron, iron carbide or carbon nitrided iron compound in described metal base; And

(ii), before the stage metal base that forms in described pretreatment stage is handled in described metal diffusing, to prevent forming oxide on surface on described surface, perhaps removed any described oxide on surface that forms on described surface.

In preferable configuration, aforesaid method can carry out in single processing stove, and wherein the DIFFUSION TREATMENT stove is also as the activation treatment stove.Yet described method can be carried out in the different stoves as activation treatment stove and DIFFUSION TREATMENT stove.

In activation stage, inert gas flow is preferably nitrogen and/or argon gas.Under the situation of being fit to, the inert particle refractory materials that uses in one or more processing stoves can be aluminum oxide or silicon carbide.

Under the situation of being fit to, when the DIFFUSION TREATMENT stove contained the inert particle refractory materials, it carried out fluidisation by inert gas flow in metal diffusing in the stage.Perhaps, such inert particle refractory materials can pass through mode of vibration fluidisation or at least part of fluidisation.In stage, preferably do not supply ammonia to the DIFFUSION TREATMENT stove in metal diffusing.

In particularly preferred embodiments, described second time period is longer than described very first time section.In this way, use the time period much shorter of relatively costly hydrogen halide at the metal base required diffusion layer of acquisition.In described diffusion phase, may not use hydrogen halide fully, but if desired, can use a small amount of hydrogen halide to reactivate metal_based material the short period of time.If desired, usually can pulse in diffusion phase the supply hydrogen halide, last time period that hydrogen halide is not provided and at least one provides the time period of hydrogen halide in burner hearth.

Under the situation of being fit to, can provide inert gas flow to the DIFFUSION TREATMENT stove in described second time period, described inert gas flow can change between the flow velocity of the incipient fluidization speed that is equal to or higher than described DIFFUSION TREATMENT stove at zero flow velocity.

Under the situation of being fit to, in activation stage and diffusion phase, the operating temperature of first and second time periods of one or more processing stoves is between 500 to 750 ℃.

In one embodiment, in described very first time section, preferably can be to activation treatment stove hydrogen halide stream without interruption.For in the mode, in described very first time section, hydrogen halide can be to comprise supply time section and the not pulse mode supply of supply time section in possible choosing.Under the situation of being fit to, employed hydrogen halide can be selected from hydrogen chloride gas, bromize hydrogen gas, hydrogen fluoride gas or hydrogen iodide gas.To activation treatment stove or the supply of DIFFUSION TREATMENT stove the time, hydrogen halide preferably mixes with inert carrier gas (for example nitrogen and/or argon gas) in one or more processing stoves outside.Under the situation of being fit to, when supply, hydrogen halide and inert carrier gas enter wherein at the place, lower region of one or more processing stoves.

In another embodiment, can be by supply ammonium chloride (NH ₄Cl) in one or more processing stoves, produce hydrogen.Ammonium chloride can be managed or pipeline supply by delivering with solid or pellets, so it is heated to be dissociated into nitrogen and hydrogenchloride (HCl) gas in delivering pipeline or pipe.Rare gas element for example nitrogen or argon gas also can be by described delivery pipe supply, makes that HCl gas is at least part of when entering stove to mix with rare gas element.Such delivery system can be used in the activation stage, perhaps is used for diffusion phase if desired.If use this delivery system, the operating temperature of stove can be near 700 ℃ or even higher temperature.

The metal_based material that is used to form the diffusing surface layer can be selected from following at least a:

(i) solid metal or metal alloy;

(ii) be coated in the metal or metal alloy on the substrate carrier;

(iii) particle or powder metal or metal alloy;

(iv) be coated in the metal or metal alloy on the inert particle refractory materials;

(v) metal halide particle or powder (anhydrous or hydration); And

(vi) be coated in the metal halide material (anhydrous or hydration) on inertia refractory particle material or the substrate carrier.

Metal_based material can be selected from chromium, titanium, vanadium, niobium, tantalum, tungsten, molybdenum, manganese and alloy thereof, comprises ferrous alloy, or the metal halide that is made of the metallic element of above-mentioned metal and the halogen root that is selected from chlorine root, bromine root, iodine root and fluorine root.

Under the situation of being fit to, metal base is ferrous metals or ferrous metals alloy.

Under the situation of being fit to, in described second time period, will import in the DIFFUSION TREATMENT stove as the nitrogen of rare gas element.

Term " metal base " plans to refer to be suitable for heat treated any metal parts by what ferrous metals or ferrous metals alloy were made.

The method according to this invention, use hydrogenchloride as halide gas and using the chromium metallics to form in the situation of diffusing surface layer, it is believed that in activation stage the chromium metallics of hydrogenchloride on aluminum oxide (inertia fluidizing medium) surface and in fluid bed furnace produces active chromium chloride.In the metal diffusing of method in the stage, between the iron surface that is rich in nitrogen of the chromium chloride of activation and metal base solid state interaction takes place, at described base material formation diffusing surface layer.This is handling stove, is taking place when being generally fluid bed furnace basically not by the inert gas flow fluidisation, and also takes place when described bed is fluidized.As known in the art, the fluidisation of bed can be carried out by suitable gas stream or by some vibration means.Described method has sizable economical advantage, because hydrogen halide, to be generally hydrogenchloride be expensive, its consumption is provided by the minimum much economic method that provides.

The external portion (white layer) of generally wishing the spreading area is substantially free of hole.Described white layer is nitrided iron, iron carbide and/or carbon nitrided iron normally, is generally ε and/or γ form.

Be described referring now to the preferred implementation of accompanying drawing to the inventive method, in described accompanying drawing:

Fig. 1 is the cross sectional representation of the fluid bed furnace that can use in enforcement of the present invention;

Fig. 2 and 3 is detailed cross sectional view of the seal arrangement that can use with the fluid bed furnace shown in Fig. 1;

Fig. 4 shows in the metal sample of the processing of producing according to the present invention of embodiment 1, and the weight % concentration of nitrogen (N), chromium (Cr) and iron (Fe) is with the variation diagram of the degree of depth;

Fig. 5 shows in the copper carrier substrate of the chromiumcoating of the activation of embodiment 1, and nitrogen (N), chromium (Cr), iron (Fe) and copper (Cu) are with the variation diagram of the degree of depth;

Fig. 6 shows in the metal sample of the processing of producing not according to the present invention of embodiment 1, and the weight % concentration of nitrogen (N), chromium (Cr) and iron (Fe) is with the variation diagram of the degree of depth;

Fig. 7 shows in the copper carrier substrate of the non-activated chromiumcoating of embodiment 1, and the weight % concentration of nitrogen (N), chromium (Cr), iron (Fe) and copper (Cu) is with the variation diagram of the degree of depth;

Fig. 8 shows in the metal sample of the processing of producing according to the present invention of embodiment 2, and the weight % concentration of chromium (Cr), iron (Fe) and nitrogen (N) is with the variation diagram of the degree of depth;

Fig. 9 shows in embodiment 2 passing through of using and carries out in the activation chromium sample of the processing that method of the present invention obtains, and the weight % concentration of chromium (Cr), iron (Fe) and nitrogen (N) is with the variation diagram of the degree of depth;

Figure 10 shows in the metal sample of the chromium sample preparation of activation in advance of no use described in the embodiment 2, and the weight % concentration of iron (Fe), nitrogen (N) and chromium (Cr) is with the variation diagram of the degree of depth;

Figure 11 is quantitative depth profile, and it shows in the metal sample of handling according to the present invention at the activation of the use described in the embodiment 3 chromium powder end, and the weight % concentration of iron (Fe), chromium (Cr), nitrogen (N), carbon (C) and oxygen (O) is with the variation of the degree of depth;

Figure 12 shows the microstructure of the metal sample (embodiment 3) of processing represented among Figure 11;

Figure 13 is the X-ray diffraction analysis, and the diffusion layer that demonstrates in the metal sample of handling (embodiment 3) mainly is CrN;

Figure 14 and 15 is quantitative depth profile, and it shows in the corresponding metal sample of handling described in the embodiment 4, and chromium (Cr), iron (Fe), nitrogen (N), carbon (C) and oxygen (O) are with the variation of the degree of depth; And

Figure 16 shows the microstructure of the metal sample of the processing of describing among the embodiment 4.

Referring now to accompanying drawing, described accompanying drawing signal has shown the associated components of the fluidized bed processor of preferred form of the present invention, can recognize from aforementioned disclosure, at least the pretreatment stage of heat treating method does not need to finish in the fluid bed heat treatment facility, can use any other known Equipment for Heating Processing in this stage.In addition, although ideally activation stage and diffusion phase are carried out in same fluidized-bed heat treatment furnace, activation and diffusion phase can be used the fluidized-bed heat treatment furnace that separates equally.

As shown in fig. 1, device comprises the fluid bed furnace 10 with inner burner hearth 11, and described inner burner hearth contains for example aluminum oxide (Al of particulate inert refractory materials 12 ₂O ₃), yet also can use other such inert refractories.Stove comprises outer insulative layer 13 and heating zone 14, and described heating zone can be with any usual manner by combustion fuel gas, by resistive heating or by any other means heating that is fit to.In the drawings, burner 16 heating of heating zone 14 by being supplied with fuel gas.Provide main rare gas element supply line 17 in burner hearth 11 bottoms, be used for making when needed refractory materials 12 fluidisations.Gas feedthroughs 17 is led to gas distributing system, and it comprises main allocated equipment 18 and secondary divider 19, and secondary divider is generally the porous material structure, is intended to prevent that gas stream from flowing in burner hearth and even therefore fluidisation and thermal treatment.Halide gas and inert carrier gas provide another gas to deliver pipeline 20, so that can import burner hearth bottoms by another divider 21 that separates with divider 18/19.Inert carrier gas (for example nitrogen and/or argon gas) can be by pipeline 70 supplies, and hydrogen halide is supplied by pipeline 71, and mix in valve 72 before delivering by pipeline 20.The amount of the hydrogen halide that can deliver to the amount of the rare gas elementes delivered by

pipeline

70 and 17 with by pipeline 71 is measured, in order to know the gas volume that is shipped to stove 10.Divider 21 can be arranged in the gross refractory district 80 of burner hearth 11 lower regions.As possibility, delivering pipeline 20 can enter by burner hearth bottom or other positions shown in dotted outline, as long as make divider 21 be arranged in the lower furnace portion zone.In this arrangement mode, deliver pipeline 20 and can shown in 20 ', upwards pass through, and before the divider 21 that halogenide and inert carrier gas is turned back in burner hearth 11 lower regions, comprise one or more heating coils 81.Be fit under the situation, heating coil 81 just is positioned at 80 tops, gross refractory district or portion within it just.Halide gas preferably fully mixes outside burner hearth 11 with inert carrier gas, and mixed gas preferably was heated before entering burner hearth.Under the situation of being fit to, by the zone with the fluidized bed processing stove heat exchange takes place and heat.In with the arrangement mode shown in the solid line, when pipeline 20 downwards during the refractory materials by heat in the burner hearth, generation is to the heating of the gas of external mix.Other arrangement modes equally also are possible.For example, in the pipeline 20 in burner hearth, can provide one or more delivery pipeline coil pipes.Perhaps, deliver pipeline 20 and can pass through heating zone 14, it has one or more coil pipes that are arranged in district 14.In the possible arrangement mode of another kind, the inert carrier gas of premix and hydrogen halide can directly enter in the stove by divider 21 discharges without preheating.Use metering and mixing equipment (not being shown specifically) to guarantee in the activation stage for the treatment of process, to use halide gas and the inert carrier gas/fluidizing agent of appropriate ratio.

Exhaust steam passage 22 is derived from the upper area of burner hearth 11, waste gas can be overflowed in a controlled manner, and handle (not shown) for the security purpose in the downstream.Some refractory materials may be overflowed along this path, and such material is collected in gravel collection box or the container 23 aptly.Sometimes, some reaction product may be solidified in this passage 22, and it finally may cause the passage obstruction that becomes.Can provide removing device 24 to strike off such material, preferably it be turned back in the collection box 23.Can use additive method rather than illustrated physics scaler.For example, can use frequently the impulsive burst of rare gas element break up or mobile exhaust steam passage 22 in material, it is got back in the burner hearth 11.Suitable granular metal or metal alloy (when using in treatment process) also can import by exhaust steam passage 22.The storage area 25 that is used for such granular metal is provided with metering valve etc. 26, so that the metal-powder of aequum or the particulate material of metallic coating are shipped in the passage 22.Then when needed, can use removing device 24, if you are using, or some puopulsion units push this metal in the burner hearth 11.This preferably carries out when bed slump (slumped) (namely not moving), and making does not have or only have seldom gas stream along passage 22 at outward direction.

As shown in fig. 1, around the top access hole 28 of burner hearth 11 inner area, provide first tightness system 27 that links to each other with covering member 29.First tightness system 27 can seal burner hearth 11 in case ambient air enters in treating processes.The characteristics of first tightness system 27 can be seen in Fig. 2 or 3 better, in described figure they are depicted as with covering member 29 operations that are used for top access hole 28.First tightness system 27 comprises the first outside seal part 30, its by the outer peripheral flange 31 on the covering member 29 with engage and form being fixed to burner hearth 11 and on the member 35 of access hole 28 two sealing material 32 between periphery and the flange 33 and 34 that radially separates.First tightness system 27 also comprises the second seal inside part 36 that is formed by outer peripheral flange 37, described outer peripheral flange 37 is carried on the member 35, and engages with sealing material 38 between the more inner outer peripheral flange 39 in the entrained position of the external flanges 31 on the covering member 29 and covering member 29.Sealing material 32 or 38 can be any compressible seal material that can operate under the relevant operating temperature of stove, but can comprise ceramic fiber or VITON(registered trademark) elastomeric material.When first tightness system 27 operability as shown in Fig. 2 a engages, between flange 31 and 37, set up seal area 40.Gas distributor pipe 41 is arranged in this district 40, and be shown as 42 pipeline by signal from outside charging, deliver nitrogen, argon gas or some other rare gas elementes with certain pressure to distinguishing 40, therefore if possible leak, such gas will leak to burner hearth opening 29, thereby stop ambient oxygen to enter burner hearth 11.Tightness system 27 also comprises the 3rd hermetic unit 43, and it is formed by interior periphery flange 39, and described flange 39 is bonded in the district 44 of the inertia refractory particle material 45 that contains the same types that comprise in common and the burner hearth 11.Particulate material 45 can be supplied fluidisation by the rare gas element of delivering to divider 47 by pipeline 46, thereby when covering member 29 moves to illustrated off-position, helps flange 39 to enter in the particulate material 45 at least.In order to enter burner hearth 11, covering member 29 is removed.This takes place when handling member (for example metal base) for example introducing or therefrom withdraw to burner hearth.

In the sealing arrangement mode shown in Figure 3, provide two

annular flanges

82,83 that erect from periphery burner hearth parts or member 35, limited seal area 84

betwixt.Flange

82,83 soldered or be fixed in burner hearth parts 35 by other means, and have different heights to obtain seal area 84.

Flange

82,83

upper limb

85,86 be pressed in the sealing material 87 that is fit in the ring groove 88 in covering member or the lid 29 and with its sealing.The edge of the upper limb 85 of the flange 82 preferably upper limb 86 than flange 83 is low, if gas make to take place from the leakage of seal area 84, it will be preferably towards inside rather than its outside leakage of burner hearth 11.Sealing material 87 can be the material with the top same type that the sealing material 32,38 of Fig. 2 a is discussed.Provide rare gas element to deliver pipe 42, rare gas element (for example nitrogen) is shipped to the divider ring 41 in the seal area 84, make when stove 10 in use and covering member 29 when closing, seal area 84 is with higher than normal atmosphere and pressurize with rare gas element than the pressure of burner hearth Nei Genggao.From the gas leakage " possibility " of seal area 84 cross flange

upper limb

85,86 both direction takes place, still, if leak really, it will preferentially be crossed edge 85 go back tos and take place to burner hearth.Therefore in burner hearth, keep required atmosphere, do not allowed undesired oxygen to enter burner hearth from outside atmosphere.From seal area 84 toward in, provide another annular flange 89, between it, have thermal insulation material 87, it can be and sealing material 87 identical materials discussed above.As shown in Figure 3, refractory particle material 91 may accumulate, but a bit when the pitch angle of this material and horizontal plane is about 60 °, crossing any under the rare gas element assistance of internal leakage of flange periphery 85 at certain, more such material will fall back in the burner hearth 11 owing to gravity.Therefore refractory materials is prevented from or remains on low-down level from the effusion of burner hearth.Under the suitable situation, it is minimum that the volume of seal area 84 keeps, to minimize the rare gas element consumption.Lid or covering member 29 have handles basket (treatment basket) (or similarly) bracing or strutting arrangement 92, and covering member 29 is insulated at least in case calorific loss under the suitable situation.In some applications, particularly when batch treatment, may also need in lid or covering member 29, comprise spiral coil cooling tube or pipeline, in order to when handling EO, when needed stove 10 is cooled down.Lid or covering member 29 can also be chosen wantonly and have stopper 93, with the space of minimization bed top.

To be described method of the present invention according to a large amount of preferable case now.In pretreatment stage, pending metal parts (or base material) is commonly called the surface treatment of nitriding or carbonitriding.This can realize by various different devices, comprises salt bath, gas thermal treatment unit, vacuum plasma equipment and fluid bed furnace.Yet ideally, the so-called white layer of setting up by this fs does not have tangible porosity basically.Other required factors also relate to concentration, the degree of depth and the microstructure of white layer, comprise wherein lacking porosity.

When producing the structure of nitrogenize or carbonitridingization, produce two districts.First inner area is the spreading area, wherein nitrogen is diffused in the base material by the spreading area and improves the hardness of base material from substrate surface, second outside area is white layer, and it can be by as constituting at the ε as shown in the international patent application no PCT/AU2006/001031 and/or γ layer.

When carrying out the pretreatment stage of the inventive method in the fluidized-bed heat treatment furnace, its control need be supplied ammonia/nitrogen (be used for nitriding) and be used for the gas that contains carbon (for example Sweet natural gas and/or carbonic acid gas) of carbonitriding to bed.During carbonitriding, importantly comprise some oxygen during the course, it can be by hydrocarbon gas, carbonic acid gas and/or oxygen contribution.In case after finishing this pretreatment stage satisfactorily, need handle pending parts or base material, to guarantee on the surface of diffuse metal therein, not having oxide on surface.In order to obtain the surface smoothness that (or keeping) is fit to, can abide by one of following option:

(i) parts or substrate surface can for example carry out mechanical treatment by polishing again, and remain under the inert atmosphere subsequently before entering subordinate phase;

(ii) pretreatment stage and activation stage and metal diffusing between the stage until and comprise and parts or substrate surface can be maintained under the inert atmosphere or in the vacuum fully in activation stage and metal diffusing stage;

(iii) in activation stage, can use the combination of halide gas and hydrogen to remove any oxide on surface that forms at parts or substrate surface; Or

(iv) can carry out wet-milling processing to parts surface, wherein can change sand grains and air and hydraulic pressure to clear up the surface.Any tectum of this process selective removal also keeps required white layer simultaneously.

In the activation stage of method, needs can be carried out the metal of surface diffusion or metal_based material and place or remain on to be lower than 750 ℃, preferably be no more than the fluid bed furnace of 700 ℃ of temperature operations.Under the suitable situation, temperature is about 575 ℃ usually in 500 ℃ to 700 ℃ scopes.Bed itself can comprise for example Al of inertia refractory particle material ₂O ₃, the metal target of wherein waiting to be diffused in the surface is taked particle or powder type in bed, or wraps alternatively by the inertia refractory particle.Such metal preferably accounts for 5 to 30 weight % of a material, and namely all the other are inert refractory.Do not having under the situation of pending metal base then, by halide gas (for example hydrogenchloride) and inert gas flow with bed fluidisation very first time section.Rare gas element can be argon gas and/or nitrogen, has the halide gas (for example HCl) that separately imports that is mixed in advance in the inert carrier gas flow (for example nitrogen and/or argon gas) simultaneously.

The metal-powder that imports in the bed preferably should have high purity and should not contain oxide on surface.Therefore, before powder enters bed and when they are retained in the bed itself, need take measures in case the air contact.It is highly purified that employed gas also needs.The rare gas element commonly used that can be used in described process is high pure nitrogen (oxygen level is lower than 10ppm), high-purity argon gas (oxygen level is lower than 5ppm), and for the processing of first pretreatment stage technical grade ammonia, it contains the water vapor that is no more than 500ppm, and before use by it is carried out further drying by siccative.Employed hydrogen halide can be technical grade HCl usually, although also can use other hydrogen halides.

Hydrogen halide accounts for 0.2 to 3% of total gas stream of entering fluidisation thermal treatment pool furnace usually.Hydrogen halide stream needs regulation and control closely, and fully mixes with inert carrier gas before entering bed.This is important for being avoided the ununiformity in the bed.Before hydrogen halide enters bed, can carry out preheating to it, in order to guarantee when it enters bed, to be in its reactive stage of tool.The preheating of halide gas and inert carrier gas has the benefit that can further reduce the amount of required hydrogen halide.Very first time section usually can be between 45 to 120 minutes, preferably between 60 to 90 minutes, to produce active layer with inertia fluidizing medium (aluminum oxide) on the diffuse metal in bed.When using chromium and hydrogen halide to be hydrogenchloride, active layer will be chromium chloride.

When this finishes in initial activation stage, pretreated metal base (carrying out pre-treatment as mentioned above) imported siege immediately or contain the siege of activated metal sill, stop halide gas stream then.In stage, the metal base that will need then to form diffusion layer thereon keeps second time period (be generally 1 to 8 hour, be preferably 4 to 8 hours) under inert gas atmosphere in the bed of activation in advance in this metal diffusing subsequently.Under the suitable situation, bed is remained below 750 ℃, aptly in 500 ℃ to 700 ℃ scopes, be generally under the about 575 ℃ temperature.In stage, fluidized-bed can have minimum inert gas flow until high inert gas flow in metal diffusing, minimum inert gas flow make its remarkable slump, high inert gas flow make its height fluidisation.Rare gas element can be nitrogen.In some cases, if think that bed needs some to reactivate, may in subordinate phase, comprise the halide gas stream of pulse.

In treatment process, in bed, namely between the various height of bed, keep relatively temperature uniformly, generally be desirable.This can change the inert gas flow that leads to bed by comprising device for detecting temperature and the temperature that detects being made response, realizes.

Be used for providing metal or the metal_based material of the metal of the diffusing surface layer that is diffused into pending metal base, can be selected from following at least a: solid metal or metal alloy, it takes particle form or as one or more solid block members; Be coated in the metal or metal alloy on the substrate carrier, wherein said substrate carrier is taked particle form or as one or more solid block members, and wherein said substrate carrier under treatment condition not with metallizing or metal alloy or pending metal base reaction; Metal halide particle or powder (anhydrous or hydration); And be coated in metal halide material (anhydrous or hydration) on the substrate carrier, wherein said substrate carrier is taked particle form or as one or more solid block members, and wherein said substrate carrier under treatment condition not with coating material or pending metal base reaction.Under the suitable situation, be used for providing the metal of the metal_based material for the treatment of diffuse metal, can be selected from chromium, titanium, vanadium, niobium, tantalum, tungsten, molybdenum, manganese and alloy thereof, comprise ferrous alloy.Under the suitable situation, the halogen root that the metal halide of censuring above can comprise selected metal above-mentioned and be selected from chlorine root, bromine root, iodine root or fluorine root.For example, CrCl ₂And CrCl ₃To form slurry, it can be coated on the suitable carrier substrate thus in water soluble and the ethanol, perhaps carrier substrate can be immersed in the suspension to form suitable coating.

Several examples of the preferred implementation of various details method.

Embodiment 1

Be that 38mm, thickness are hardened and tempered (1020 ℃ of austenitizings (autenitised) and the air cooling of 5mm with diameter, 575 ℃ of dual tempering) sample of AISI H13 Hot Work Tool Steel, in 35% ammonia, 5% carbonic acid gas, 60% nitrogen atmosphere, 575 ℃ of following carbonitridings 3.5 hours.Before carbonitriding, use 1200 grades of SiC abrasive materials that this sample surfaces is prepared, to guarantee surface of good smooth finish.This produced by directly 10 microns by 1 micron oxygen enrichment upper layer on the compound layer that ε-the carbon nitrided iron constitutes, and be the surface tissue that the internal divergence district of 70-90 micron constitutes at last.Then vapour blasting is carried out to remove oxide skin in the surface of this carbonitriding sample, keep compound layer and spreading area simultaneously.In compound layer, the composition of chromium is about 4 weight % after measured.

The fine copper piece of diameter 38mm, thickness 5mm is polished to 1200 grades of SiC smooth finish, electroplates the hard chrome that comes from commercialization supplier then.Produce 2 microns pure chromium layer by this method.Selecting copper is that therefore during heating the chromium layer can not decompose by being diffused in the copper sample because Cr is insoluble basically with Cu as substrate carrier.Then this chromium plating sample being immersed in diameter 90mm, degree of depth 250mm and containing the 3kg median size is that 125 microns, purity are in the fluid bed heat treatment reactor of 99.99% alumina powder.This fluidized-bed is heated to 575 ℃ under nitrogen, and to add hydrogen chloride gas to concentration to the input gas stream under this temperature be 1% of total gas stream.Should " activation " stage continue 1 hour time.Behind this activation stage, the plating chrome on copper layer sample is cooled to room temperature in nitrogen gas stream.

After taking out from fluidized-bed reactor and entering the ambient air conditions, immediately with plating chrome on copper layer sample and the carbonitriding sample physical bond of hydrogenchloride activation, and apply clamping pressure.Then this conjunction is placed fluid bed furnace, and under nitrogen gas stream, be heated to 575 ℃, under this temperature, kept 4 hours, under nitrogen gas stream, be cooled to room temperature then.The conjunction that is made of the plating chrome on copper layer that does not carry out the hydrogenchloride processing as mentioned above and carbonitriding sample is repeated this experiment.After untiing combination, use glow discharge luminescent spectrum art (GDOES) to analyze the chemical constitution of two surface in contacts.

Find, by using surface, this surface and the carbonitriding example reaction of hydrogen chloride gas activation plating chrome on copper layer sample.Chromium from the activation the chromium plating sample transfer to carbonitriding sample (Fig. 4), consumed the chromium (Fig. 5) on the plating chrome on copper layer sample.Chromium is made response in the lip-deep enrichment of carbonitriding, and nitrogen is to surface diffusion, to produce the peak (Fig. 4) consistent with the chromium peak.Iron from the carbonitriding sample to chromium plating sample transfer (Fig. 5).Correspondingly, the concentration of iron on the carbonitriding sample is consumed (Fig. 4).On the contrary, between non-activated plating chrome on copper layer and carbonitriding surface, do not react.Do not observe the lip-deep chromium enrichment of carbonitriding (Fig. 6) or chromium from the consumption (Fig. 7) of plating chrome on copper layer sample.The hydrogenchloride surface active that this embodiment shows chromium to the chromium metal from the chromium source importance of the transfer to the surface region that is rich in nitrogen.

Embodiment 2

Be that 38mm, thickness are hardened and tempered (1020 ℃ of austenitizings and the air cooling of 5mm with diameter, 575 ℃ of dual tempering) sample of AISI H13 Hot Work Tool Steel, in 35% ammonia, 5% carbonic acid gas, 60% nitrogen atmosphere, 575 ℃ of following carbonitridings 3.5 hours.Before carbonitriding, use 1200 grades of SiC abrasive materials that this sample surfaces is prepared, to guarantee surface of good smooth finish.This produced by directly 10 microns by 1 micron oxygen enrichment upper layer on the compound layer that ε-the carbon nitrided iron constitutes, and be the surface tissue that the internal divergence district of 70-90 micron constitutes at last.Then vapour blasting is carried out to remove oxide skin in the surface of this carbonitriding sample, keep compound layer and spreading area simultaneously.In compound layer, the composition of chromium is about 4 weight % after measured.

Be that 99.99% chromium piece is polished to 1200 grades of SiC with the purity of diameter 38mm, thickness 5mm, being immersed in diameter 90mm, degree of depth 250mm then and containing the 3kg median size is that 125 microns, purity are in the fluidized-bed reactor of 99.99% alumina powder.This fluidized-bed is heated to 575 ℃ under nitrogen, and to add hydrogen chloride gas to concentration to the input gas stream under this temperature be 1% of gas stream.Should " activation " stage continue 1 hour time.Behind this activation stage, the chromium sample is cooled to room temperature in nitrogen gas stream.

After taking out from fluidized-bed reactor and entering the ambient air conditions, immediately with chromium sample and the carbonitriding sample physical bond of hydrogenchloride activation, and apply clamping pressure.Then this conjunction is placed fluid bed furnace, and under nitrogen gas stream, be heated to 575 ℃, under this temperature, kept 4 hours, under nitrogen gas stream, be cooled to room temperature then.The conjunction that is made of the chromium that does not carry out the hydrogenchloride processing and carbonitriding sample is repeated this experiment.After untiing combination, use glow discharge luminescent spectrum art (GDOES) to analyze the chemical constitution of two surface in contacts.

Identical with embodiment 1, by using surface, this surface and the carbonitriding example reaction of hydrogen chloride gas activation chromium.Chromium is diffused into described surface from the chromium sample transfer of activation to carbonitriding sample and nitrogen, to produce the peak (Fig. 8) consistent with the chromium peak.Iron from the carbonitriding sample to chromium plating sample transfer (Fig. 9).Correspondingly, the concentration of iron on the carbonitriding sample is consumed (Fig. 8).On the contrary, do not reacting between the chromium of activation and the carbonitriding surface in advance.Do not observe the lip-deep chromium enrichment of carbonitriding (Figure 10).

Embodiment 3

Be that 38mm, thickness are hardened and tempered (1020 ℃ of austenitizings and air coolings of two of 5mm with diameter, 575 ℃ of dual tempering) AISI H13 hot forged mould steel sample, in 35% ammonia, 5% carbonic acid gas, 60% nitrogen atmosphere, 575 ℃ of following carbonitridings 3.5 hours.Before carbonitriding, use 1200 grades of SiC abrasive materials that the surface of each sample is prepared, to guarantee surface of good smooth finish.This produced by directly 10 microns by 1 micron oxygen enrichment upper layer on the compound layer that ε-the carbon nitrided iron constitutes, and be the surface tissue that the internal divergence district of 70-90 micron constitutes at last.Then vapour blasting is carried out to remove oxide skin in the surface of carbonitriding sample, keep compound layer and spreading area simultaneously.In compound layer, the composition of chromium is about 4 weight % after measured.

Being that 90mm, the degree of depth are in the fluidized-bed reactor of 250mm at diameter, is that 80 microns and purity be 99.99% chromium powder end with the 3.4kg median size are that 125 microns and purity are that 99.99% alumina powder mixes with the 380g median size.This fluidized-bed is enough to carry out at flow be heated to 575 ℃ under the high-purity nitrogen of fluidisation, and under this temperature, the carbonitriding AISH13 sample of as above preparation is immersed in the fluidized powder of heating 4 hours time period.Sample is cooled to 350 ℃ under nitrogen gas stream, in fluidized-bed, and in air, cools off.As the result of this process, the carbonitriding surface does not experience the chromium enrichment.

Being that 90mm, the degree of depth are in the fluidized-bed reactor of 250mm at diameter, is that 80 microns and purity be 99.99% chromium powder end with the 3.4kg median size are that 125 microns and purity are that 99.99% alumina powder mixes with the 380g median size.This fluidized-bed is enough to carry out at flow be heated to 575 ℃ under the high-purity nitrogen of fluidisation, and to add hydrogen chloride gas to concentration to the input gas stream under this temperature be 1% of gas stream.Should " activation " stage continue 1 hour time.After this activation, the carbonitriding AISH13 sample that as above prepares is immersed in the fluidized powder of heating, stop hydrogen chloride gas stream simultaneously, 4 hours time period is carried out in thermal treatment under 575 ℃.Then sample is cooled to 350 ℃ under nitrogen gas stream, in fluidized-bed, and in air, cools off.In this test, the significant chromium enrichment (about 70 weight % are referring to the quantitative depth profile of Figure 12) of carbonitriding surface experience forms unique, equal layer (Figure 12) of even continuous 2.5 micron thickness.This layer of X-ray diffraction analysis revealed is mainly CrN(Figure 13).

Embodiment 4

To be higher than 575 ℃ possibility in order assessing process temperature brought up to, to have selected to have two kinds of other steel of level of the tempering resistance higher than AISI H13 Hot Work Tool Steel.Be that 38mm, thickness are hardened and tempered (1050 ℃ of austenitizings and with oil annealing, 575 ℃ of dual tempering) powder metallurgy die steel Crucible CPM of 5mm with diameter

With the metallurgical steel Bohler-Uddeholm of conventional mold

90 sample is in 35% ammonia, 5% carbonic acid gas, 60% nitrogen atmosphere, 575 ℃ of following carbonitridings 3.5 hours.Before carbonitriding, use 1200 grades of SiC abrasive materials that each sample surfaces is prepared, to guarantee surface of good smooth finish.This produced by directly 10 microns by 1 micron oxygen enrichment upper layer on the compound layer that ε-the carbon nitrided iron constitutes, and be the surface tissue that the internal divergence district of 70-90 micron constitutes at last.Then vapour blasting is carried out to remove oxide skin in the surface of carbonitriding sample, keep compound layer and spreading area simultaneously.In compound layer, the composition of chromium is about 4 weight % after measured.

Being that 90mm, the degree of depth are in the fluidized-bed reactor of 250mm at diameter, is that 80 microns and purity be 99.99% chromium powder end with the 3.4kg median size are that 125 microns and purity are that 99.99% alumina powder mixes with the 380g median size.This fluidized-bed is enough to carry out at flow be heated to 625 ℃ under the high-purity nitrogen of fluidisation, and to add hydrogen chloride gas to concentration to the input gas stream under this temperature be 1% of gas stream.Should " activation " stage continue 1 hour time.After activation, with as above the preparation every kind of grade a carbonitriding sample the heating fluidized powder in, 4 hours time period of submergence under high-purity nitrogen.Sample is cooled to 350 ℃ under nitrogen gas stream, in fluidized-bed, takes out and air, cool off from fluidized-bed reactor then.In this test, the experience significant chromium enrichment (about 70 weight % are referring to the quantitative depth profile of Figure 14 and 15) of carbonitriding surface has corresponding nitrogen peak.Compare with the processing under 575 ℃, under 625 ℃, carry out the chromium deposition stage and cause layer thickness to be increased to about 4-6 micron (Figure 15).Below the CrN layer, spreading area and core hardness have been kept basically.

Claims

1. form the method for the diffusing surface layer that extends internally from the outside surface of metal base, described method comprises:

2. the process of claim 1 wherein that described activation treatment stove is identical with described DIFFUSION TREATMENT stove.

3. the process of claim 1 wherein that described DIFFUSION TREATMENT stove is different with described activation treatment stove.

4. each method of claim 1 to 3, it also comprises:

(i) in pretreatment stage, the described spreading area that formation extends internally from the surface of metal base, nitrogen has been spread to form described externalizing compound layer or the white layer of described internal divergence district and nitrided iron, iron carbide or carbon nitrided iron compound in described metal base; And

5. each method of claim 1 to 4, the inert gas flow in the wherein said activation stage is nitrogen and/or argon gas.

6. each method of claim 1 to 5, wherein said inert particle refractory materials is aluminum oxide or silicon carbide.

7. each method of claim 1 to 6, wherein said DIFFUSION TREATMENT stove contain at described metal diffusing inert particle refractory materials by the inert gas flow fluidisation in the stage.

8. each method of claim 1 to 6, wherein said DIFFUSION TREATMENT stove contain at described metal diffusing inert particle refractory materials by at least part of fluidisation of mode of vibration in the stage.

9. each method of claim 1 to 8, wherein described metal diffusing in the stage to DIFFUSION TREATMENT stove supply ammonia.

10. each method of claim 1 to 9, wherein said second time period is longer than described very first time section.

11. each method of claim 1 to 10 wherein in described second time period, to described DIFFUSION TREATMENT stove pulse supply hydrogen halide stream, is lasted time period of not having hydrogen halide stream and the time period of at least one hydrogen halide stream.

12. each method of claim 1 to 11, wherein said DIFFUSION TREATMENT stove contains the inert particle refractory materials, and provide inert gas flow to described DIFFUSION TREATMENT stove in described second time period, described inert gas flow can and be equal to or higher than between the flow velocity of incipient fluidization speed of described DIFFUSION TREATMENT stove at zero flow velocity and change.

13. each method of claim 1 to 12, wherein the temperature of keeping in described activation treatment stove between 500 ℃ to 750 ℃ is lasted described first predetermined amount of time.

14. each method of claim 1 to 13, wherein the temperature of keeping in described DIFFUSION TREATMENT stove between 500 ℃ to 750 ℃ is lasted described second predetermined amount of time.

15. each method of claim 1 to 14 is wherein in described first predetermined amount of time, to described activation treatment stove described hydrogen halide without interruption.

16. each method of claim 1 to 14 wherein in described first predetermined amount of time, is supplied described hydrogen halide by the pulse mode that supply time section not separates to described activation treatment stove with the supply time section.

17. each method of claim 1 to 16, wherein said hydrogen halide is selected from hydrogen chloride gas, bromize hydrogen gas, hydrogen fluoride gas and hydrogen iodide gas.

18. each method of claim 1 to 14, wherein said hydrogen halide mixed with described rare gas element before entering the activation treatment stove.

19. each method of claim 1 to 14, wherein said hydrogen halide mixed with described rare gas element before entering the DIFFUSION TREATMENT stove.

20. the process of claim 1 wherein and supply ammonium chloride to described activation treatment stove in described activation stage, described ammonium chloride is heated to resolve into nitrogen and hydrogen chloride gas when being imported into, and is used for the activation of described metal_based material.

21. claim 18,19 or the method for claim 20, wherein the mixture of hydrogen halide and rare gas element enters described activation treatment stove or DIFFUSION TREATMENT stove at the place, lower region of activation treatment stove or DIFFUSION TREATMENT stove.

22. each method of claim 1 to 21, the metal_based material that wherein is used to form the diffusing surface layer is selected from following at least a:

(i) solid metal or metal alloy;

(ii) be coated in the metal or metal alloy on the substrate carrier;

(iii) particle or powder metal or metal alloy;

(v) metal halide particle or powder (anhydrous or hydration); And

23. each method of claim 1 to 22, the metal_based material that wherein is used to form the diffusing surface layer is selected from chromium, titanium, vanadium, niobium, tantalum, tungsten, molybdenum, manganese and alloy thereof, comprise ferrous alloy, or the metal halide that is constituted by the metallic element of above-mentioned metal and the halogen root that is selected from chlorine root, bromine root, iodine root and fluorine root.

24. each method of claim 1 to 23, wherein said metal base is ferrous metals or ferrous metals alloy.

25. each method of claim 1 to 24, wherein in described second predetermined amount of time, the described rare gas element that is imported in the described DIFFUSION TREATMENT stove is nitrogen.