CA2298046A1 - Boronizing agent in paste form - Google Patents
Boronizing agent in paste form Download PDFInfo
- Publication number
- CA2298046A1 CA2298046A1 CA002298046A CA2298046A CA2298046A1 CA 2298046 A1 CA2298046 A1 CA 2298046A1 CA 002298046 A CA002298046 A CA 002298046A CA 2298046 A CA2298046 A CA 2298046A CA 2298046 A1 CA2298046 A1 CA 2298046A1
- Authority
- CA
- Canada
- Prior art keywords
- boronizing
- boronizing agent
- paste
- agent according
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/60—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes
- C23C8/62—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes only one element being applied
- C23C8/68—Boronising
- C23C8/70—Boronising of ferrous surfaces
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Paints Or Removers (AREA)
- Lubricants (AREA)
- Ceramic Products (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
- Production Of Multi-Layered Print Wiring Board (AREA)
- Details Of Reciprocating Pumps (AREA)
- Carbon And Carbon Compounds (AREA)
- Saccharide Compounds (AREA)
- Detergent Compositions (AREA)
- Chemically Coating (AREA)
Abstract
This invention relates to a boronizing agent in the form of a paste for the production of boride layers on metallic workpieces, which boronizing agent comprises boron-releasing substances, activating substances, and the remainder of inert refractory extenders together with water, and optionally, auxiliaries required for paste formulation. It also contains as additives:
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
This boronizing paste causes no corrosive attack on the component surface and exhibits improved storage stability.
The agent gives rise to reduced fluorine or fluoride emissions. The boronizing agent may be removed in a simple manner. Single-phase boride layers containing Fe2B may in particular be produced on workpieces made from ferrous material.
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
This boronizing paste causes no corrosive attack on the component surface and exhibits improved storage stability.
The agent gives rise to reduced fluorine or fluoride emissions. The boronizing agent may be removed in a simple manner. Single-phase boride layers containing Fe2B may in particular be produced on workpieces made from ferrous material.
Description
Boronizing Agent In Paste Form This invention relates to a boronizing agent in the form of a paste for the production of boride layers on metallic materials. The purpose of this paste is in particular to produce single-phase, hard and tenacious boride layers on ferrous materials in order to increase wear resistance and in order to improve the corrosion resistance of such workpieces.
Boronizing has long been known as a process for protecting iron, steel and refractory metals from wear. Dense, uniform layers of the particular boride, for example the borides FeB, Fe2B on iron, are produced by elemental boron diffusing into the surface of the workpiece being treated and reacting with the base material. In comparison with the pure metals, the borides have considerably modified properties, in particular most borides are very hard, corrosion-resistant and thus extremely wear-resistant.
Since they are produced by diffusion and a solid-state reaction, the boride layers are solidly bonded to. the base material. With regard to wear resistance, some boronized steels are, for example, superior to steels treated by nitriding or carburizing.
Numerous means and industrial processing variants have accordingly been developed in the past by means of which boride layers may be produced, in particular on steel.
In practice, boronizing is predominantly performed in solid boronizing agents. In this case, the parts to be treated are packed in iron boxes in powder mixtures which substantially consist of boron-releasing substances, activating substances with the remainder being inert, refractory extenders. The sealed boxes are heat treated for a certain period, wherein the desired boride layers are formed on the parts in a direct solid-state reaction or by transport of the boron in the gas phase.
Boronizing is conventionally performed at temperatures of between 800 and 1100°C, and in particular between 850 and 950°C. Achievable layer thicknesses of the boride layers are normally in the range between 30 and 300 Vim.
Boron-releasing substances which may be considered for boronizing agents are amorphous and crystalline boron, ferroboron, boron carbide and borates such as borax.
Suitable activating substances are chloride- or fluoride-releasing compounds such as alkali metal and alkaline earth metal chlorides or fluorides. Fluoroborates, such as in particular potassium tetrafluoroborate, are particularly widely used as activators. Typical extenders are aluminium oxide, silicon dioxide and silicon carbide. Boronizing agents of this type are described, for example, in DE-PS
17 96 216. A typical composition which has hitherto proved successful as a boronizing agent contains approx. 5 wt.o of boron carbide, 5 wt.% of potassium tetrafluoroborate and 90 wt.% of silicon carbide. Boronizing agents of the stated type are normally used as powder mixtures. They may, however, also be formulated as pellets (for example DE-OS
21 27 096) or as pastes (for example DE-OS 26 33 137). In the case of pellets and pastes, the compositions also contain subordinate quantities of binders and water respectively.
Processes have furthermore been developed which operate with gaseous boronizing agents such as diborane, boron halides or, alternatively, in molten salt baths with boron carbide and borax as the boron-releasing substances. These latter-stated processes have not become well established due to the toxicity of the compounds and due to processing disadvantages, such as the elaborate control measures required to ensure a uniform boronizing action. Recent attempts to produce boride layers using plasma processes are not suitable for all applications due to the influences of charging and complex geometric shapes. Plant and equipment costs are moreover very high. Solid boronizing agents, some of which are also used in paste form, thus still retain their dominant position for surface boronizing since they have the advantages of being simple to use and providing good boride layers.
The commonest boronizing processes using known solid boronizing agents do, however, have the disadvantage that they demand highly elaborate processing technology in order to produce single-phase iron boride layers in particular on ferrous materials (c.f. for example EP 0 387 536 B1).
Since the two borides Fe2B and FeB have differing properties and multi-phase layers usually have poorer properties than single-phase layers, efforts are made to produce single-phase layers when boronizing.
Thus, in particular, the FeB phase, which has a higher boron content, is substantially brittler than the Fe2B
phase, which has a negative influence on the wear.
resistance of the boronized components. In boride layers thicker than 50 Vim, an FeB case is also readily formed, which should, if at all possible, be avoided for the stated reason.
Using hitherto known boronizing pastes, it has previously been possible under conventional processing conditions to obtain single-phase layers only of a thickness of less than 50 Vim. If thicker boride layers are to be obtained, it is necessary to perform post-diffusion by a complex heat treatment operation under a vacuum or in a salt bath or special boronizing agents are required (for example according to German patent application 198 30 654.7).
Moreover, fluoride emissions are found in the exhaust gases from conventional boronizing pastes. Both post-diffusion and fluoride emissions result in layer porosity, which has a negative impact on layer properties.
With many materials, known boronizing pastes result in corrosive attack on the coated workpiece during the drying phase. As a result, paste residues adhere so strongly to the surface of the workpiece after treatment that cleaning the components with water is not sufficient and an additional jet cleaning operation is required, wherein there is also a risk that the boride layer which has been produced will also be affected. Such corrosive attack may be so severe that it has not previously been possible to use paste boronizing on certain grades of steel as it results in corrosive loss of material.
Known boronizing pastes are not stable in storage, in particular at elevated temperatures, due to dissociation of the activator KBF4 accompanied by a reduction in pH.
The object of the invention was accordingly to provide a boronizing agent in the form of paste with which, in particular on ferrous materials, virtually exclusively single-phase boride layers containing FezB may be produced.
Moreover, the intention was also that the content of water-soluble fluorides should be reduced in these boronizing agents in paste form and that correct use should be accompanied by reduced fluoride emissions. In particular, the intention was also to reduce the porosity of the boride layer formed. The intention was moreover to prevent corrosive attack and thus also facilitate cleaning of the components. The intention was additionally to improve the storage stability of the boronizing paste.
It has surprisingly now been found that, in boronizing agents in paste form which substantially consist of boron-releasing substances, activating substances and the remainder of inert, refractory extenders together with water and optionally auxiliaries required for paste formulation, these disadvantages may be overcome by the addition of small quantities of certain additives.
It has firstly been discovered that the porosity of the boride layer may be distinctly reduced by the addition of 5 alkali metal or alkaline earth metal carbonates, for example calcium carbonate. This brings about extended component service life. Hydrogen fluoride emissions are additionally reduced by fluorides, for example HF, being bound as CaF2. The optionally produced CaF2 moreover brings about the positive effects described in German patent application 198 30 654.7.
It has moreover been discovered that corrosive attack by the boronizing paste on all investigated grades of steel may be completely suppressed by the addition of alkali metal or alkaline earth metal nitrites, for example sodium nitrite. As a result, not only may higher surface qualities be achieved, but it is also possible to treat steels which could not hitherto be paste boronized. In contrast, testing with other known corrosion-protective agents did not meet with success; indeed, more severe corrosion sometimes occurred than in the absence of conventional corrosion-protective additives.
It has furthermore been discovered that an improvement in storage stability of the boronizing paste may be achieved by the addition of water-soluble alkali metal or alkaline earth borates, for example sodium tetraborate (borax). The inevitable dissociation of the activator KBF4 in water results in the formation of HF and thus in acidification of the paste with increased corrosive attack and possible instability of paste auxiliaries, such as the thickener.
This is completely suppressed by the addition of borate.
The storage stability of the boronizing paste is consequently substantially extended. Attempts to prevent a reduction in the pH value solely by addition of soluble carbonates, such as for example sodium carbonate, modified the viscosity and rheological properties of the paste, so having a negative impact on the use thereof.
It has furthermore been found that cleaning of the components and the surface appearance may be improved by addition of borate, as it forms a very thin, glaze-like film on the component, so facilitating removal of the paste after boronizing. In addition to the corrosion protection described above, it is consequently also possible to avoid jet cleaning of the components after boronizing, The invention accordingly provides a boronizing agent in the form of a paste for the production of boride layers on metallic workpieces, which boronizing agent comprises boron-releasing substances; activating substances;
refractory extenders; water; optionally auxiliaries required for paste formulation; and these additives:
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
The boronizing paste according to the invention preferably contains, relative to the solids content, 0.1-5 wt.% of compounds according to (a), 0.1-2 wt.o of compounds according to (b) and 0.1-2 wt.°s of compounds according to (c) .
The boronizing paste in particular contains, relative to the solids content, 1-3 wt.o of compounds according to (a), 0.2-1 wt.% of compounds according to (b) and 0.2-1 wt.% of compounds according to (c).
The carbonates of sodium, potassium, calcium and magnesium may in particular be considered as compounds according to (a). Calcium carbonate is. particularly preferred.
Alkali metal nitrites, such as in particular sodium and potassium nitrite, are preferably considered as compounds according to (b). Sodium nitrite is particularly preferred.
Alkali metal borates, such as in particular sodium and potassium borate, are considered from the group of compounds according to (c). Sodium tetraborate (borax) is particularly preferred.
The boronizing paste according to the invention preferably contains boron carbide as the boron-releasing substance, potassium tetrafluoroborate as the activating substance and silicon carbide as the extender.
In a particularly preferred embodiment, the boronizing paste contains a combination of potassium tetrafluoroborate and calcium fluoride as the activating substance.' It has, in fact, furthermore been found that the type of boride formation in the workpiece surface may purposefully be influenced and controlled by a boronizing agent of a per se conventional composition, to which, in addition to conventional activator substances, calcium fluoride is added as a further activating substance. In this manner, it is straightforwardly possible, without any other elaborate processing measures, to produce virtually FeB-free, single-phase Fe2B layers on workpieces made from ferrous materials.
Further investigation has revealed that when KBF4 is completely replaced by CaF2 in conventional prior art boronizing agents, inadequate boride layers are formed on the surfaces of the workpiece under normal processing conditions. The same happens if, in order to reduce fluorine emissions, the content of KBF4 in the boronizing agent is simply reduced.
The boronizing paste according to the invention conveniently contains as activating substance a combination of 1 to 15 wt.% of potassium tetrafluoroborate and 5 to 40 wt.o of calcium fluoride, in each case relative to the solids content.
The boronizing agent in paste form according to the invention may contain conventional boron-releasing substances, such as amorphous or crystalline ferroboron and in particular boron carbide (B4C). It preferably contains 1 to 15 wt.% of boron carbide, relative to the solids content.
The remainder of the boronizing paste according to the invention furthermore contains usual extenders, such as in particular silicon carbide (SiC), together with water and optionally auxiliaries.
The boronizing paste according to the invention preferably contains, relative to the solids content, 8 to 10 wt.o of boron carbide, 5 to 10 wt.% of potassium tetrafluoroborate, 10 to 30 wt.o of calcium fluoride, 1-3 wt.% of calcium carbonate, 0.2-1 wt.% of sodium nitrite, 0.2-1 wt.% of sodium tetraborate and the remainder silicon carbide as extender, together with water and optionally auxiliaries.
A typical composition consists approximately of 10 wt.% of boron carbide, 7 wt.o of potassium tetrafluoroborate, 15 wt.% of calcium fluoride, 1.5 wt.% of calcium carbonate, 0.5 wt.% of sodium nitrite, 0.5 wt.o of sodium tetraborate and the remainder of silicon carbide, relative to the solids content.
Boronizing has long been known as a process for protecting iron, steel and refractory metals from wear. Dense, uniform layers of the particular boride, for example the borides FeB, Fe2B on iron, are produced by elemental boron diffusing into the surface of the workpiece being treated and reacting with the base material. In comparison with the pure metals, the borides have considerably modified properties, in particular most borides are very hard, corrosion-resistant and thus extremely wear-resistant.
Since they are produced by diffusion and a solid-state reaction, the boride layers are solidly bonded to. the base material. With regard to wear resistance, some boronized steels are, for example, superior to steels treated by nitriding or carburizing.
Numerous means and industrial processing variants have accordingly been developed in the past by means of which boride layers may be produced, in particular on steel.
In practice, boronizing is predominantly performed in solid boronizing agents. In this case, the parts to be treated are packed in iron boxes in powder mixtures which substantially consist of boron-releasing substances, activating substances with the remainder being inert, refractory extenders. The sealed boxes are heat treated for a certain period, wherein the desired boride layers are formed on the parts in a direct solid-state reaction or by transport of the boron in the gas phase.
Boronizing is conventionally performed at temperatures of between 800 and 1100°C, and in particular between 850 and 950°C. Achievable layer thicknesses of the boride layers are normally in the range between 30 and 300 Vim.
Boron-releasing substances which may be considered for boronizing agents are amorphous and crystalline boron, ferroboron, boron carbide and borates such as borax.
Suitable activating substances are chloride- or fluoride-releasing compounds such as alkali metal and alkaline earth metal chlorides or fluorides. Fluoroborates, such as in particular potassium tetrafluoroborate, are particularly widely used as activators. Typical extenders are aluminium oxide, silicon dioxide and silicon carbide. Boronizing agents of this type are described, for example, in DE-PS
17 96 216. A typical composition which has hitherto proved successful as a boronizing agent contains approx. 5 wt.o of boron carbide, 5 wt.% of potassium tetrafluoroborate and 90 wt.% of silicon carbide. Boronizing agents of the stated type are normally used as powder mixtures. They may, however, also be formulated as pellets (for example DE-OS
21 27 096) or as pastes (for example DE-OS 26 33 137). In the case of pellets and pastes, the compositions also contain subordinate quantities of binders and water respectively.
Processes have furthermore been developed which operate with gaseous boronizing agents such as diborane, boron halides or, alternatively, in molten salt baths with boron carbide and borax as the boron-releasing substances. These latter-stated processes have not become well established due to the toxicity of the compounds and due to processing disadvantages, such as the elaborate control measures required to ensure a uniform boronizing action. Recent attempts to produce boride layers using plasma processes are not suitable for all applications due to the influences of charging and complex geometric shapes. Plant and equipment costs are moreover very high. Solid boronizing agents, some of which are also used in paste form, thus still retain their dominant position for surface boronizing since they have the advantages of being simple to use and providing good boride layers.
The commonest boronizing processes using known solid boronizing agents do, however, have the disadvantage that they demand highly elaborate processing technology in order to produce single-phase iron boride layers in particular on ferrous materials (c.f. for example EP 0 387 536 B1).
Since the two borides Fe2B and FeB have differing properties and multi-phase layers usually have poorer properties than single-phase layers, efforts are made to produce single-phase layers when boronizing.
Thus, in particular, the FeB phase, which has a higher boron content, is substantially brittler than the Fe2B
phase, which has a negative influence on the wear.
resistance of the boronized components. In boride layers thicker than 50 Vim, an FeB case is also readily formed, which should, if at all possible, be avoided for the stated reason.
Using hitherto known boronizing pastes, it has previously been possible under conventional processing conditions to obtain single-phase layers only of a thickness of less than 50 Vim. If thicker boride layers are to be obtained, it is necessary to perform post-diffusion by a complex heat treatment operation under a vacuum or in a salt bath or special boronizing agents are required (for example according to German patent application 198 30 654.7).
Moreover, fluoride emissions are found in the exhaust gases from conventional boronizing pastes. Both post-diffusion and fluoride emissions result in layer porosity, which has a negative impact on layer properties.
With many materials, known boronizing pastes result in corrosive attack on the coated workpiece during the drying phase. As a result, paste residues adhere so strongly to the surface of the workpiece after treatment that cleaning the components with water is not sufficient and an additional jet cleaning operation is required, wherein there is also a risk that the boride layer which has been produced will also be affected. Such corrosive attack may be so severe that it has not previously been possible to use paste boronizing on certain grades of steel as it results in corrosive loss of material.
Known boronizing pastes are not stable in storage, in particular at elevated temperatures, due to dissociation of the activator KBF4 accompanied by a reduction in pH.
The object of the invention was accordingly to provide a boronizing agent in the form of paste with which, in particular on ferrous materials, virtually exclusively single-phase boride layers containing FezB may be produced.
Moreover, the intention was also that the content of water-soluble fluorides should be reduced in these boronizing agents in paste form and that correct use should be accompanied by reduced fluoride emissions. In particular, the intention was also to reduce the porosity of the boride layer formed. The intention was moreover to prevent corrosive attack and thus also facilitate cleaning of the components. The intention was additionally to improve the storage stability of the boronizing paste.
It has surprisingly now been found that, in boronizing agents in paste form which substantially consist of boron-releasing substances, activating substances and the remainder of inert, refractory extenders together with water and optionally auxiliaries required for paste formulation, these disadvantages may be overcome by the addition of small quantities of certain additives.
It has firstly been discovered that the porosity of the boride layer may be distinctly reduced by the addition of 5 alkali metal or alkaline earth metal carbonates, for example calcium carbonate. This brings about extended component service life. Hydrogen fluoride emissions are additionally reduced by fluorides, for example HF, being bound as CaF2. The optionally produced CaF2 moreover brings about the positive effects described in German patent application 198 30 654.7.
It has moreover been discovered that corrosive attack by the boronizing paste on all investigated grades of steel may be completely suppressed by the addition of alkali metal or alkaline earth metal nitrites, for example sodium nitrite. As a result, not only may higher surface qualities be achieved, but it is also possible to treat steels which could not hitherto be paste boronized. In contrast, testing with other known corrosion-protective agents did not meet with success; indeed, more severe corrosion sometimes occurred than in the absence of conventional corrosion-protective additives.
It has furthermore been discovered that an improvement in storage stability of the boronizing paste may be achieved by the addition of water-soluble alkali metal or alkaline earth borates, for example sodium tetraborate (borax). The inevitable dissociation of the activator KBF4 in water results in the formation of HF and thus in acidification of the paste with increased corrosive attack and possible instability of paste auxiliaries, such as the thickener.
This is completely suppressed by the addition of borate.
The storage stability of the boronizing paste is consequently substantially extended. Attempts to prevent a reduction in the pH value solely by addition of soluble carbonates, such as for example sodium carbonate, modified the viscosity and rheological properties of the paste, so having a negative impact on the use thereof.
It has furthermore been found that cleaning of the components and the surface appearance may be improved by addition of borate, as it forms a very thin, glaze-like film on the component, so facilitating removal of the paste after boronizing. In addition to the corrosion protection described above, it is consequently also possible to avoid jet cleaning of the components after boronizing, The invention accordingly provides a boronizing agent in the form of a paste for the production of boride layers on metallic workpieces, which boronizing agent comprises boron-releasing substances; activating substances;
refractory extenders; water; optionally auxiliaries required for paste formulation; and these additives:
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
The boronizing paste according to the invention preferably contains, relative to the solids content, 0.1-5 wt.% of compounds according to (a), 0.1-2 wt.o of compounds according to (b) and 0.1-2 wt.°s of compounds according to (c) .
The boronizing paste in particular contains, relative to the solids content, 1-3 wt.o of compounds according to (a), 0.2-1 wt.% of compounds according to (b) and 0.2-1 wt.% of compounds according to (c).
The carbonates of sodium, potassium, calcium and magnesium may in particular be considered as compounds according to (a). Calcium carbonate is. particularly preferred.
Alkali metal nitrites, such as in particular sodium and potassium nitrite, are preferably considered as compounds according to (b). Sodium nitrite is particularly preferred.
Alkali metal borates, such as in particular sodium and potassium borate, are considered from the group of compounds according to (c). Sodium tetraborate (borax) is particularly preferred.
The boronizing paste according to the invention preferably contains boron carbide as the boron-releasing substance, potassium tetrafluoroborate as the activating substance and silicon carbide as the extender.
In a particularly preferred embodiment, the boronizing paste contains a combination of potassium tetrafluoroborate and calcium fluoride as the activating substance.' It has, in fact, furthermore been found that the type of boride formation in the workpiece surface may purposefully be influenced and controlled by a boronizing agent of a per se conventional composition, to which, in addition to conventional activator substances, calcium fluoride is added as a further activating substance. In this manner, it is straightforwardly possible, without any other elaborate processing measures, to produce virtually FeB-free, single-phase Fe2B layers on workpieces made from ferrous materials.
Further investigation has revealed that when KBF4 is completely replaced by CaF2 in conventional prior art boronizing agents, inadequate boride layers are formed on the surfaces of the workpiece under normal processing conditions. The same happens if, in order to reduce fluorine emissions, the content of KBF4 in the boronizing agent is simply reduced.
The boronizing paste according to the invention conveniently contains as activating substance a combination of 1 to 15 wt.% of potassium tetrafluoroborate and 5 to 40 wt.o of calcium fluoride, in each case relative to the solids content.
The boronizing agent in paste form according to the invention may contain conventional boron-releasing substances, such as amorphous or crystalline ferroboron and in particular boron carbide (B4C). It preferably contains 1 to 15 wt.% of boron carbide, relative to the solids content.
The remainder of the boronizing paste according to the invention furthermore contains usual extenders, such as in particular silicon carbide (SiC), together with water and optionally auxiliaries.
The boronizing paste according to the invention preferably contains, relative to the solids content, 8 to 10 wt.o of boron carbide, 5 to 10 wt.% of potassium tetrafluoroborate, 10 to 30 wt.o of calcium fluoride, 1-3 wt.% of calcium carbonate, 0.2-1 wt.% of sodium nitrite, 0.2-1 wt.% of sodium tetraborate and the remainder silicon carbide as extender, together with water and optionally auxiliaries.
A typical composition consists approximately of 10 wt.% of boron carbide, 7 wt.o of potassium tetrafluoroborate, 15 wt.% of calcium fluoride, 1.5 wt.% of calcium carbonate, 0.5 wt.% of sodium nitrite, 0.5 wt.o of sodium tetraborate and the remainder of silicon carbide, relative to the solids content.
The boronizing agent in paste form according to the invention may, for example, be formulated from the corresponding powder mixture by addition of water and optionally subordinate quantities of auxiliaries, such as conventional commercial binders and/or thickeners.
Depending upon the requirement of the particular application, the water content may amount to 25 to 40 wt.%, relative to the total quantity. The paste preferably contains 30 to 35 wt.% and in particular approximately 30 wt.% of water.
Further auxiliaries which may be considered are thickeners and binders as are conventional when formulating pastes.
Bentonite is a particularly suitable thickener. This material is used in the boronizing paste in a small quantity, typically of approximately 1 wt.%, relative to the total quantity.
The boronizing paste according to the invention may highly advantageously be used for the production of boride layers on metallic workpieces.
Addition of carbonate, reduces the porosity of the boride layer and thus increases the durability of the components.
The addition of nitrite eliminates the tendency of known boronizing pastes towards corrosive attack of the component. This results in very good surface appearance.
Since, in comparison with known compositions, it has proved possible to reduce the content of KBF4 by partially replacing it with the water-insoluble CaFz, the boronizing agent according to the invention is substantially less critical with regard to fluoride emissions, especially in relation to the disposal of waste water after washing boronized components and of spent boronizing agent. A
reduced KBFq content is furthermore advantageous when the boronizing agent is used correctly as correspondingly lower gaseous emissions containing fluorine are generated. The addition of carbonate still further reduces these emissions, so increasing the environmental compatibility of the process. The problems of known boronizing pastes with regard to storage stability are overcome by the addition of 5 borate. The borate, together with the added nitrite, also results in substantially easier cleaning of the components than with known boronizing pastes.
One particular processing advantage of the boronizing paste according to the invention is that single-phase boride l0 layers containing FeZB and having a low pore content may straightforwardly and simply be produced on workpieces made from ferrous materials. This is attributable to the preferable selection of a combination of 1 to 15 wt.o of potassium tetrafluoroborate and 5 to 40 wt.% of calcium fluoride, relative to the quantity of the solids in the boromizing~ paste, as the activating substance.
In the process according to the invention for the production of preferably single-phase boride layers containing Fe2B and having a low pore content on workpieces made from ferrous materials, the surface of the workpieces is covered with the boronizing paste and treatment is then performed at temperatures of between 800 and 1100°C until a boride layer of the desired thickness has formed. To this end, the surface of the parts is brushed with the boronizing agent paste. This is particularly advantageous in the event that an only partially boronized surface is desired. The boronizing agent may alternatively also be applied by dipping the parts in the paste or by spraying on the paste.
Boronizing preferably proceeds at temperatures of between 850 and 980°C over a period of 20 minutes to 2 hours. In this manner, single-phase FeZB layers of a thickness of 30 to 150 ~m may be obtained.
Example 1:
Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste of the following composition according to the invention:
30 % water; 7 . 5 % B4C; 5 % KBF4; 10 % CaF2; 45 % SiC; 1 % CaC03;
0.3% NaN02; 0.4% borax; 0.8% bentonite (thickener).
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 50 um. Even after extended storage at elevated temperature, the paste exhibited no change in processing characteristics. The pH
value was approx. 7.5.
Example 2: (Comparative Example) Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing~ paste of the following conventional composition:
30% water; 7.5% B4C; 9.2% KBF4; 52.5% SiC; 0.8% bentonite (thickener) .
After the heat treatment, the boronizing agent could not be removed completely without leaving residues; adequate cleaning of the components was achieved only after brushing or jet cleaning. The components exhibited slight signs of corrosive attack and severe staining. The boride layer was of a thickness of approx. 50 Vim, but was of two phases; FeB
needles reached down to a depth of 14 Vim. In comparison with Example 1, a thicker pore fringe was observed. After extended storage at elevated temperature, the viscosity of the paste had fallen and relatively severe sedimentation of the solids had occurred. The pH value of the paste was approx. 4.
Example 3:
Components made from the material Cf52 were boronized for S 60 minutes at 940°C under protective gas using a boronizing paste of the following composition according to the invention:
30% water; 7. 5% B4C; 5% KBF4; 10% CaFz; 45 o SiC; 1% CaC03;
0.3% NaNOz; 0.4% borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 70 ~.m.
Example 4:
Components made from the material C 60 were boronized for 120 minutes at 950°C under protective gas using a boronizing paste of the following composition according to the invention:
30% water; 7.5% B4C; 5% KBF4; 10% CaF2; 45% SiC; 1% CaC03;
0.3% NaN02; 0.4% borax; 0.8o bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues; the component exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 140 um.
Example S:
Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste of the following composition according to the invention:
30 % water; 7. 5 % B4C; 8 % KBF4; 50 % SiC; 3 % CaC03; 0 . 3 % NaN02;
0.4% borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 52 ~.m. Emissions of fluorine compounds were approx. 25% greater than those from Example 1.
Example 6: (Comparative Example) Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste containing neither calcium carbonate nor calcium fluoride and of the following composition:
30 % water; 7. 5 % B4C; 9% KBF4; 52 % SiC; 0 . 3 % NaN03; 0 . 4 %
borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer, of a thickness of approx.
50 Vim, was two-phase and FeB needles reached down to a depth of 10 ~,m. The layer more highly porous than in 2S Example 5. Emissions of fluorine compounds were approx. 40%
greater than those from Example 1.
Depending upon the requirement of the particular application, the water content may amount to 25 to 40 wt.%, relative to the total quantity. The paste preferably contains 30 to 35 wt.% and in particular approximately 30 wt.% of water.
Further auxiliaries which may be considered are thickeners and binders as are conventional when formulating pastes.
Bentonite is a particularly suitable thickener. This material is used in the boronizing paste in a small quantity, typically of approximately 1 wt.%, relative to the total quantity.
The boronizing paste according to the invention may highly advantageously be used for the production of boride layers on metallic workpieces.
Addition of carbonate, reduces the porosity of the boride layer and thus increases the durability of the components.
The addition of nitrite eliminates the tendency of known boronizing pastes towards corrosive attack of the component. This results in very good surface appearance.
Since, in comparison with known compositions, it has proved possible to reduce the content of KBF4 by partially replacing it with the water-insoluble CaFz, the boronizing agent according to the invention is substantially less critical with regard to fluoride emissions, especially in relation to the disposal of waste water after washing boronized components and of spent boronizing agent. A
reduced KBFq content is furthermore advantageous when the boronizing agent is used correctly as correspondingly lower gaseous emissions containing fluorine are generated. The addition of carbonate still further reduces these emissions, so increasing the environmental compatibility of the process. The problems of known boronizing pastes with regard to storage stability are overcome by the addition of 5 borate. The borate, together with the added nitrite, also results in substantially easier cleaning of the components than with known boronizing pastes.
One particular processing advantage of the boronizing paste according to the invention is that single-phase boride l0 layers containing FeZB and having a low pore content may straightforwardly and simply be produced on workpieces made from ferrous materials. This is attributable to the preferable selection of a combination of 1 to 15 wt.o of potassium tetrafluoroborate and 5 to 40 wt.% of calcium fluoride, relative to the quantity of the solids in the boromizing~ paste, as the activating substance.
In the process according to the invention for the production of preferably single-phase boride layers containing Fe2B and having a low pore content on workpieces made from ferrous materials, the surface of the workpieces is covered with the boronizing paste and treatment is then performed at temperatures of between 800 and 1100°C until a boride layer of the desired thickness has formed. To this end, the surface of the parts is brushed with the boronizing agent paste. This is particularly advantageous in the event that an only partially boronized surface is desired. The boronizing agent may alternatively also be applied by dipping the parts in the paste or by spraying on the paste.
Boronizing preferably proceeds at temperatures of between 850 and 980°C over a period of 20 minutes to 2 hours. In this manner, single-phase FeZB layers of a thickness of 30 to 150 ~m may be obtained.
Example 1:
Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste of the following composition according to the invention:
30 % water; 7 . 5 % B4C; 5 % KBF4; 10 % CaF2; 45 % SiC; 1 % CaC03;
0.3% NaN02; 0.4% borax; 0.8% bentonite (thickener).
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 50 um. Even after extended storage at elevated temperature, the paste exhibited no change in processing characteristics. The pH
value was approx. 7.5.
Example 2: (Comparative Example) Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing~ paste of the following conventional composition:
30% water; 7.5% B4C; 9.2% KBF4; 52.5% SiC; 0.8% bentonite (thickener) .
After the heat treatment, the boronizing agent could not be removed completely without leaving residues; adequate cleaning of the components was achieved only after brushing or jet cleaning. The components exhibited slight signs of corrosive attack and severe staining. The boride layer was of a thickness of approx. 50 Vim, but was of two phases; FeB
needles reached down to a depth of 14 Vim. In comparison with Example 1, a thicker pore fringe was observed. After extended storage at elevated temperature, the viscosity of the paste had fallen and relatively severe sedimentation of the solids had occurred. The pH value of the paste was approx. 4.
Example 3:
Components made from the material Cf52 were boronized for S 60 minutes at 940°C under protective gas using a boronizing paste of the following composition according to the invention:
30% water; 7. 5% B4C; 5% KBF4; 10% CaFz; 45 o SiC; 1% CaC03;
0.3% NaNOz; 0.4% borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 70 ~.m.
Example 4:
Components made from the material C 60 were boronized for 120 minutes at 950°C under protective gas using a boronizing paste of the following composition according to the invention:
30% water; 7.5% B4C; 5% KBF4; 10% CaF2; 45% SiC; 1% CaC03;
0.3% NaN02; 0.4% borax; 0.8o bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues; the component exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 140 um.
Example S:
Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste of the following composition according to the invention:
30 % water; 7. 5 % B4C; 8 % KBF4; 50 % SiC; 3 % CaC03; 0 . 3 % NaN02;
0.4% borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer was FeB-free, had a low pore content and a thickness of approx. 52 ~.m. Emissions of fluorine compounds were approx. 25% greater than those from Example 1.
Example 6: (Comparative Example) Components made from the material 42CrMo4 were boronized for 45 minutes at 930°C under protective gas using a boronizing paste containing neither calcium carbonate nor calcium fluoride and of the following composition:
30 % water; 7. 5 % B4C; 9% KBF4; 52 % SiC; 0 . 3 % NaN03; 0 . 4 %
borax; 0.8% bentonite.
After the heat treatment, the boronizing agent could be removed simply with water without leaving any residues and the components exhibited neither signs of corrosive attack nor stains. The boride layer, of a thickness of approx.
50 Vim, was two-phase and FeB needles reached down to a depth of 10 ~,m. The layer more highly porous than in 2S Example 5. Emissions of fluorine compounds were approx. 40%
greater than those from Example 1.
Claims (18)
1. A boronizing agent in the form of a paste for the production of boride layers on metallic workpieces, comprising: boron-releasing substances, activating substances, inert refractory extenders and water; and containing as additives:
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
(a) at least one compound from the group of alkali metal and alkaline earth metal carbonates;
(b) at least one compound from the group of alkali metal and alkaline earth metal nitrites;
(c) at least one compound from the group of water-soluble alkali metal and alkaline earth metal borates.
2. The boronizing agent according to claim 1, comprising, relative to the solids content:
0.1-5 wt.% of compounds according to (a);
0.1-2 wt.% of compounds according to (b); and 0.1-2 wt.% of compounds according to (c).
0.1-5 wt.% of compounds according to (a);
0.1-2 wt.% of compounds according to (b); and 0.1-2 wt.% of compounds according to (c).
3. The boronizing agent according to claim 1, comprising, relative to the solids content:
1-3 wt.% of compounds according to (a);
0.2-1 wt.% of compounds according to (b); and 0.2-1 wt.% of compounds according to (c).
1-3 wt.% of compounds according to (a);
0.2-1 wt.% of compounds according to (b); and 0.2-1 wt.% of compounds according to (c).
4. The boronizing agent according to claim 1, 2 or 3, wherein (a) is at least one compound selected from the group of alkaline earth carbonates.
5. The boronizing agent according to claim 1, 2 or 3, wherein (a) is calcium carbonate.
6. The boronizing agent according to any one of claims 1 to 5, wherein (b) is at least one compound selected from the group of alkali metal nitrites.
7. The boronizing agent according to any one of claims 1 to 5, wherein (b) is sodium nitrite.
8. The boronizing agent according to any one of claims 1 to 7, wherein (c) is at least one compound selected from the group of alkali metal borates.
9. The boronizing agent according to any one of claims 1 to 7, wherein (c) is sodium tetraborate.
10. The boronizing agent according to any one of claims 1 to 9, wherein:
the boron-releasing substance is boron carbide;
the activating substance is potassium tetrafluoroborate;
and the extender is silicon carbide.
the boron-releasing substance is boron carbide;
the activating substance is potassium tetrafluoroborate;
and the extender is silicon carbide.
11. The boronizing agent according to any one of claims 1 to 10, wherein the activating substance is a combination of potassium tetrafluoroborate and calcium trifluoride.
12. The boronizing agent according to claim 11, comprising:
1 to 15 wt.% of boron carbide as the boron-releasing substance; and a combination of 1 to 15 wt.% of potassium tetrafluoro-borate, and 5 to 40 wt.% of calcium fluoride, in each case relative to the solids content, as the activating substance.
1 to 15 wt.% of boron carbide as the boron-releasing substance; and a combination of 1 to 15 wt.% of potassium tetrafluoro-borate, and 5 to 40 wt.% of calcium fluoride, in each case relative to the solids content, as the activating substance.
13. The boronizing agent according to any one of claims 1 to 9, comprising, relative to the solids content:
8 to 10 wt.% of boron carbide;
to 10 wt.% of potassium tetrafluoroborate;
to 30 wt.% of calcium fluoride;
1-3 wt.% of calcium carbonate;
0.2-1 wt.% of sodium nitrite;
0.2-1 wt.% of sodium tetraborate; and the remainder silicon carbide.
8 to 10 wt.% of boron carbide;
to 10 wt.% of potassium tetrafluoroborate;
to 30 wt.% of calcium fluoride;
1-3 wt.% of calcium carbonate;
0.2-1 wt.% of sodium nitrite;
0.2-1 wt.% of sodium tetraborate; and the remainder silicon carbide.
14. The boronizing agent according to any one of claims 1 to 9, comprising, relative to the solids content:
10 wt.% of boron carbide;
7 wt.% of potassium tetrafluoroborate;
wt.% of calcium fluoride;
1.5 wt.% of calcium carbonate;
0.5 wt.% of sodium nitrite;
0.5 wt.% of sodium tetraborate; and the remainder of silicon carbide.
10 wt.% of boron carbide;
7 wt.% of potassium tetrafluoroborate;
wt.% of calcium fluoride;
1.5 wt.% of calcium carbonate;
0.5 wt.% of sodium nitrite;
0.5 wt.% of sodium tetraborate; and the remainder of silicon carbide.
15. The boronizing agent according to any one of claims 1 to 14, also including auxiliaries for paste formulation.
16. Use of a boronizing agent in paste form according to any one of claims 1 to 14 for the production of boride layers containing Fe2B and having a low pore content on workpieces made from ferrous materials.
17. A process for the production of boride layers containing Fe2B and having a low pore content on a workpiece made from ferrous materials, comprising the steps of:
covering the surface of the workpiece with the boronizing paste according to any one of claims 1 to 14; and treating the workpiece at a temperature of between 800 and 1100°C until a boride layer of the desired thickness has formed.
covering the surface of the workpiece with the boronizing paste according to any one of claims 1 to 14; and treating the workpiece at a temperature of between 800 and 1100°C until a boride layer of the desired thickness has formed.
18. The process according to claim 17, wherein, in order to produce Fe2B layers of a thickness of 30 µm to 150 µm, treatment is performed at temperatures of between 850°C
and 950°C over a period from 20 minutes to 2 hours.
and 950°C over a period from 20 minutes to 2 hours.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19904629A DE19904629C2 (en) | 1999-02-05 | 1999-02-05 | Paste-shaped borating agent, its use and method for producing low-pore Fe¶2¶B-containing boride layers |
| DE19904629.8 | 1999-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2298046A1 true CA2298046A1 (en) | 2000-08-05 |
Family
ID=7896498
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002298046A Abandoned CA2298046A1 (en) | 1999-02-05 | 2000-02-04 | Boronizing agent in paste form |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP1026282B1 (en) |
| JP (1) | JP4360728B2 (en) |
| AT (1) | ATE234946T1 (en) |
| BR (1) | BR0000249B1 (en) |
| CA (1) | CA2298046A1 (en) |
| CZ (1) | CZ295247B6 (en) |
| DE (2) | DE19904629C2 (en) |
| TR (1) | TR199903326A2 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1314828C (en) * | 2004-11-23 | 2007-05-09 | 江苏工业学院 | Method and apparatus for DC electric field accelerating solid powder boriding |
| JP2007297650A (en) * | 2006-04-27 | 2007-11-15 | Fuji Kihan:Kk | Boronization method |
| GB0819298D0 (en) | 2008-10-21 | 2008-11-26 | Wellstream Int Ltd | Flexible pipe having increased acid resistance and/or corrosion resistance |
| CN102154616A (en) * | 2011-03-23 | 2011-08-17 | 常州大学 | Boronizing method and device for inner surface of tubular component by using direct-current electric field enhanced powder method |
| CN102409287A (en) * | 2011-12-01 | 2012-04-11 | 常州大学 | Direct-current electric field enhanced powder alumetizing method of inner surface of tubular part and device for same |
| KR101523546B1 (en) * | 2015-02-16 | 2015-05-28 | 한영선재(주) | Method for manufacturing non phosphate coated metal material for cold heading plastic working |
| US10870912B2 (en) | 2017-03-14 | 2020-12-22 | Bwt Llc | Method for using boronizing reaction gases as a protective atmosphere during boronizing, and reaction gas neutralizing treatment |
| US11192792B2 (en) | 2017-03-14 | 2021-12-07 | Bwt Llc | Boronizing powder compositions for improved boride layer quality in oil country tubular goods and other metal articles |
| CN115094370A (en) * | 2022-07-05 | 2022-09-23 | 山东九环石油机械有限公司 | Special anti-corrosion wear-resistant boronizing petroleum pipe and manufacturing method thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1258372A (en) * | 1969-01-21 | 1971-12-30 | ||
| CH556394A (en) * | 1970-07-28 | 1974-11-29 | Bopp Anton | PROCESS FOR SURFACE HARDENING OF STEELS AND SINTER HARD METALS. |
| BE789036A (en) * | 1971-09-24 | 1973-03-20 | Kempten Elektroschmelz Gmbh | BORING AGENT |
| DD140676B1 (en) * | 1978-12-14 | 1983-06-08 | Horst Kemnitz | POWDERFUL BORING AGENT |
| US4555326A (en) * | 1984-05-17 | 1985-11-26 | Betz Laboratories, Inc. | Methods and compositions for boronizing metallic surfaces |
-
1999
- 1999-02-05 DE DE19904629A patent/DE19904629C2/en not_active Expired - Lifetime
- 1999-12-30 TR TR1999/03326A patent/TR199903326A2/en unknown
-
2000
- 2000-01-12 EP EP00100550A patent/EP1026282B1/en not_active Expired - Lifetime
- 2000-01-12 AT AT00100550T patent/ATE234946T1/en active
- 2000-01-12 DE DE50001473T patent/DE50001473D1/en not_active Expired - Lifetime
- 2000-02-01 CZ CZ2000366A patent/CZ295247B6/en not_active IP Right Cessation
- 2000-02-02 BR BRPI0000249-6A patent/BR0000249B1/en not_active IP Right Cessation
- 2000-02-04 CA CA002298046A patent/CA2298046A1/en not_active Abandoned
- 2000-02-04 JP JP2000028339A patent/JP4360728B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| TR199903326A2 (en) | 2000-09-21 |
| ATE234946T1 (en) | 2003-04-15 |
| BR0000249B1 (en) | 2009-01-13 |
| DE19904629A1 (en) | 2000-08-10 |
| BR0000249A (en) | 2000-10-17 |
| JP2000226647A (en) | 2000-08-15 |
| JP4360728B2 (en) | 2009-11-11 |
| EP1026282A2 (en) | 2000-08-09 |
| CZ295247B6 (en) | 2005-06-15 |
| DE50001473D1 (en) | 2003-04-24 |
| EP1026282A3 (en) | 2000-10-18 |
| EP1026282B1 (en) | 2003-03-19 |
| CZ2000366A3 (en) | 2000-12-13 |
| DE19904629C2 (en) | 2003-08-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6503344B2 (en) | Boronizing agent in paste form | |
| US3728188A (en) | Chrome-free deoxidizing and desmutting composition and method | |
| US6245162B1 (en) | Boriding agent | |
| CA2298046A1 (en) | Boronizing agent in paste form | |
| US3770512A (en) | Method for surface hardening steel and cemented carbides | |
| US5290365A (en) | Method for removing coatings from metal substrates prone to corrosion or deterioration | |
| US3623921A (en) | Composition for preventing braze and diffusion flow | |
| US5589220A (en) | Method of depositing chromium and silicon on a metal to form a diffusion coating | |
| WO2008100155A1 (en) | Self-protective boron containing paste and application of this on metal components | |
| CN114836711A (en) | Metal surface hardening method | |
| CN116200697B (en) | Process method for carbonitriding curtain wall steel member thermal spraying aluminum alloy coating | |
| US6197436B1 (en) | Method and composition for diffusion alloying of ferrous materials | |
| MXPA00001170A (en) | Paste boriding agent | |
| CA1128378A (en) | Process for producing vanadium carbide layers on iron | |
| US4956016A (en) | Anticorrosive agents and use thereof | |
| CA1133806A (en) | Detergent phosphatizer composition and method of using same | |
| WO2020091695A1 (en) | A solid boriding agent | |
| JPS6070169A (en) | Salt bath for producing antiabrasive boride layer nonelectrically | |
| CA2269735A1 (en) | Method and composition for diffusion alloying of ferrous materials | |
| KR920004015B1 (en) | Boronising pastes and boronising treatment method of ferrous and ferrous-alloy surfaces | |
| MXPA99006327A (en) | Borify agent | |
| SU1047993A1 (en) | Composition for chemical heat treatment of steel articles | |
| RU2221078C2 (en) | Method of treatment of steel articles | |
| KR940003096B1 (en) | Surface hardening process and carbide forming agent of metallic surface | |
| SU1164314A1 (en) | Powder-like composition for borating carbon steel articles |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |