CA2086868C - Hard facing casting surfaces with wear-resistant sheets - Google Patents
Hard facing casting surfaces with wear-resistant sheetsInfo
- Publication number
- CA2086868C CA2086868C CA002086868A CA2086868A CA2086868C CA 2086868 C CA2086868 C CA 2086868C CA 002086868 A CA002086868 A CA 002086868A CA 2086868 A CA2086868 A CA 2086868A CA 2086868 C CA2086868 C CA 2086868C
- Authority
- CA
- Canada
- Prior art keywords
- wear
- sheet
- resistant
- pins
- metal
- 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.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/08—Casting in, on, or around objects which form part of the product for building-up linings or coverings, e.g. of anti-frictional metal
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/10—Alloys containing non-metals
- C22C1/1036—Alloys containing non-metals starting from a melt
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
- Y10T428/12049—Nonmetal component
- Y10T428/12056—Entirely inorganic
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
- Y10T428/12063—Nonparticulate metal component
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
- Y10T428/12063—Nonparticulate metal component
- Y10T428/12139—Nonmetal particles in particulate component
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
- Y10T428/12146—Nonmetal particles in a component
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Laminated Bodies (AREA)
- Mold Materials And Core Materials (AREA)
- Paper (AREA)
Abstract
A method for impregnating a metal product with a hard wear-resistant surface area comprises providing a wear-resistant layer in the form of a sintered sheet having at least one "pin" integrally attached onto a surface of the sheet. This wear-resistant layer is attached onto the sand core and a metal melt is cast so as to produce the final product. This method can be used to produce a variety of metal products although cast iron, and in particular, ductile iron are preferred. Moreover, this process can effectively employ any of the hard phases which can be sintered, e.g., tungsten carbide, chromium carbide, and the like. Preferably, both the sheet and the "pins"
are made from the same mixture of a wear-resistant material, an organic binder, and at least one plasticizer.
are made from the same mixture of a wear-resistant material, an organic binder, and at least one plasticizer.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a process for the impregnation of a metal product with a surface comprising a hard wear-resistant material.
A wide variety of techniques are known for the impregnation of metals, e.g., iron, with a hard wear-resistant surface. Such techniques include flame spray coating and plasma spray coating. However, each of these spray coating techniques suffer from problems associated with the ~p~lling of surface layers during the coating process and during service as well as the particularly large expense associated with the use of this technique.
Cast-in-carbides are also known in which carbide particulates are placed in a mold and molten iron is then cast. See, for example, the discussion within U.S. Patent No. 4,119,459 to Eckmar et al. It is difficult, however, with such castings to accurately maintain the carbide particles in the desired location and in a regular distribution pattern.
In addition, certain cast-on hard surfacing techniques for use with polystyrene patterns are also known in the art. See, for example, the discussion in Hansen et al., "Application of Cast-On Ferrochrome-Based Hard Surfacing to Polystyrene Pattern C~ting~," Bureau of Mines Report of Investigations 8942, U.S. Department of the Interior, 1985.
However, this process suffers from problems associated with the low reliability of the bond formed between the wear-resistant layer, e.g., tungsten carbide, and the foam pattern. Because of this failure, the iron may 208686~
not penetrate the layer before the iron solidifies and thus, instead of impregnating the iron, the carbide spalls off the product.
The inventor of the present invention has also been involved in inventing other processes in an attempt to more effectively impregnate the 5 surface of a metal, e.g., iron, with hard phases during the casting process.
For example, attention is directed toward U.S. Patent No. 5,027,878 to Revankar et al which relates to the carbide impregnation of cast iron using evdpoldtive pattern c~ctingC (EPC) as well as U.S. Application Serial Numbers 564,184 and 564,185 which relate to the i~"plegnation of cast iron 10 and aluminum alloy castings with carbides using sand cores.
However, despite their effectiveness, these methods also have certain drawbacks. For example, the EPC method may involve the inct~ tion of special equipment in a conventional foundry. Furthermore, c~ctin~c produced by this process can suffer from distortion due to the distortion of 15 the plastic foam replicas. On the other hand, the above sand core methods of casting carbides can involve the preparation of carbide spheres which adds to the cost of the process. The cost can be further increased if a substantially flat wear-resistant surface is desired because in such a case, a surface layer equal in thickness to half the sphere ~ met~r or more will need 20 to be machined off.
Accordingly, the need still exists for a method of impregn~ting metal surfaces, and in particular iron surfaces with a hard wear-resistant material which is capable of overcoming the problems associated with known techniques.
SUMMARY OF THE INVENTION
In one aspect of the present invention, there is disclosed a method for impregnating a metal product with a hard wear-resistant material surface layer which involves the use of "pins" or "hooks" made from the wear-resistant material and which enable the wear-resistant material surface layer to be "mechanically" attached to the casting surface.
In one aspect, the present invention relates to a method for impregnating a metal product with a hard wear-resistant surface layer comprising:
(a) providing a wear-resistant layer in the form of a sintered sheet having at least one pin integrally attached onto the surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt, which metal does not metallurgically react with the wear-resistant layer, so as to produce a metal product having a wear-resistant metal surface layer, wherein at least one pin, upon casting, forms a mechanical bond between the wear-resistant layer and the coating surface.
In another aspect, the present invention relates to the product produced by this method.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a sintered carbide sheet containing four carbide "pins" according to the present invention.
-3a-Fig. 2 illustrates suitable shapes for the carbide pins which are employed in the present invention.
Fig. 3 is a photograph illustrating a ductile iron casting showing a carbide sheet having a "hook" or "pin" forming an integral part of the sheet.
s DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention can be employed for casting virtually any type of metal which is known within the art. However, cast iron, and in particular, ductile or grey iron are plefelled. Other examples of suitable metals include non-ferrous alloys and superalloys.
In the present invention, an initial step involves the formation of a sheet comprising a wear-resistant material. As to the choice of the hard wear-resistant material, the present invention can effectively employ any of the hard phases which can be sintered, such as tungsten carbide, chromium carbide, and the like. Furthermore, this wear-resistant material can include a metallic binder, such as those of the Fe group, preferably Co for use with ngsten carbide, or Ni for chromium carbide, and the like. For example, where ductile iron is employed as the metal to be cast, particles composing tllng~ten carbide with 14-17 weight ~ cobalt is preferred.
The sheet is formed by mixing a powder of the hard wear-resistant material (optionally containing a metallic binder) with a suitable organic binder, for example, a 10% polyvinyl alcohol (PVA) solution, and a suitable plasticizer, for example, 2-ethylhexyl diphenyl phosphate, phosphate ester plasticizer (e.g., KRONITEX 3600 of FMC Corporation) or a mixture of plasticizers so as to form a slip which has appro~liate rheological characteristics such that it can be formed into a sheet. In this regard, suitable binders and/or plasticizers include any which can be effectively S employed with the particular wear-resistant material.
In this process, fine particles of the wear resistant material are preferably employed, i.e., -140/200 and finer mesh size.
The outer surface of the sheet is then preferably patterned into a texture which allows for better impregnation into the iron. The shape of the 10 pattern within the sheet is any pattern which will effectively prevent the lateral movement of the sheet from component surface during use, i.e., to allow it to resist any shear force that may be applied tangentially to the sheet surface. For example, in one embodiment, a "waMe" texture is patterned onto the outer surface of the sheet. See, for example, Fig. 1.
Moreover, this pattern can be formed by any suitable means, for example, by pressing a die with the required pattern onto the surface of the sheet while the sheet is still green and in the plastic state.
The same wear-resistant material/organic binder/plasticizer mixture employed in producing the sheet is also preferably employed in forming the 20 "pins" or "hooks" which are to be attached to the sheets. The shape of these "pins" or "hooks" is any shape which allows it to "mechanically" hold the wear-resistant material sheet onto the casting surface. Two examples of suitable pin shapes are illustMted by Fig. 2. Other pin shapes can include, e.g., flat "sheets" of carbides, also having a waMe surface texture.
These pins are cast separately and then dried, e.g., in an oven at, e.g., 100~C so as to become a "rigid" solid. These pins are planted onto the 5 sheet and in particular, onto the side of the sheet containing the pattern so as to forrn the wear-resistant layer. See, for example, the arrangement illustrated in Fig. 1.
The number of pins which need to be attached to the sheet is that n~eS~ry to overcome the force of separation that may be applied to the 10 sheet surface. For example, in the embodiment illustMted by Fig. 1, four hooks are employed although, the number can vary from, e.g., 1-8 pins.
These pins can be attached after they are dried, or, they can be presintered and then attached onto the sheets. In either technique, they become an integMI part of the sheets when the sheets themselves are sintered 15 along with the attached pins. These sheets are then heated at low ~"~pe~ res e.g., 320-340~C to partially remove organic binder and plasticizer.
This sintering of the "green" sheet occurs under conditions so as to allow the sheet and the pins to become fully dense. Suitable sintering 20 conditions are recognized in the art and include, for example, that occurring in a vacuum at 1450-1475~C for 50-75 minutes.
Re~use the composition of the pin is prefeMbly identical to that of the sheet, the sintered sheet with the hooks attached is effectively stress-free when cooled to room temperature from the sintering temperature and thus, the pins form an integral part of the sheets subsequent to sintering. See, for example, the cross-section illustrated in Fig. 3.
Though the above described method uses binder and plasticizer to 5 form sheets and pins there may be other methods which may not use these organic additives. Thus for example, the carbide powder with a suitable propo"ion of metallic binder may be directly pressed into a sheet with a flat pin in a cold die press. Such sheets may then be sintered following the same procedure as for making carbide sheets using organic binders and plasticizers 10 except, of course, that the step for removal of binder and plasticizer by heating at lower te,-,peldtures is unnecessa.y.
The sintel~d wear-resistant layer is then attached onto a suitable mold surface, e.g., a sand core by means which are recognized within the art.
For example, in one embodiment, a high te"~pe,ature adhesive is employed 15 and the layer is then heated in, e.g., an oven at 100~C so as to drive moisture from the adhesive and cure it.
By high te",pe,dture, it is meant that the adhesive has a melting point higher than the metal pouring temperature. Any suitable adhesive can be employed within the present invention with high temperature inorganic 20 adhesive being p-ef~ d.
In the preferred embodiment employing ductile iron as the metal, the binder comprises a high temperature ceramic adhesive, AREMCO's Ceramabond 569, which is a proprietary high temperature binder that includes oxides of aluminum, silicon and potassium, as a colloidal sllspen~ion in water and which has a maximum use temperature of about 1650~C (Ceramabond is a trademark of AREMCO Products, Inc.).
At this point, the liquid metal is cast around the hard wear-resistant 5 layer using any of the casting techniques traditionally employed in the art, e.g., gravity feed casting, squeeze casting, vacuum casting or the like.
However, due to the ease of use, the gravity feed of metal is p-efelled. An exemplary ductile iron casting with tungsten carbide impregnation is illustrated in Fig. 3.
The method according to the present invention can be used to produce metal products which have a wide variety of applications. Furthermore, as discu~ce~ above, this process may be applied to a variety of metals and alloys thereof because the process does not require that the metal react metallurgically with the wear-resistant material sheet. However, in the 15 specific case of cast iron, there is found a metallurgical reaction which further strengthens iron-carbide bonding. This reaction can be facilitated by the waMe pattern on the sheet.
Moreover, the process of the present invention can provide these products at a greatly reduced cost when compared with prior art systems. In 20 particular, the surface modification can be effectively accomplished during the casting process without requiring any subsequent brazing or welding and without requiring additional casting facilities such as that associated with the 20~6868 EPC system. In fact, this process can be easily adapted to existing sand casting foundry practices.
In order to further illustrate the present invention and the advantages associated therewith, the following specific example is given, it being 5 understood that same is intended only as illustrated and in no wise limitative.
20~6868 Example Fine tungsten carbide/14-17% cobalt powder (-140~200 or finer mesh size) is mixed with a suitable binder such as a 10% aqueous polyvinyl alcohol solution and a suitable plasticizer (2-ethylhexyl diphenyl phosphate or S KRONITEX 3600 of FMC Corporation) or a mixture of plasticizers to form a slip with appl~liate rheological characteristics so it can be cast or rolled into a sheet. The sheet surface is patterned into a "waMe" texture as shown in Fig. 1, before the sheets become rigid through drying or curing.
Using the same carbide/binder/plasticizer mixture, pins of a suitable 10 shape (see Fig. 2) are cast separately and are dried in an oven at 100~C
when they become rigid solids. These pins are planted into the above carbide sheets on the waffle pattern side of the sheet as shown in Fig. 1, while the sheets are still plastic, i.e., before the binder resin hardens. The green carbide sheets are then sintered in vacuum at 1460~C for 60 minutes 15 when the sheet and the pins become fully dense. See Figure 3.
The sintered carbide sheet is then attached to a sand core using Aremco's Ceramabond 569 and the core/sheet is heated in an oven at 100~C
to drive out the moisture from the binder and cure it. It may also be dried at room te,l,pe,dture provided sufficiently long curing time is allowed. The 20 cast iron is cast around the sheet using the conventional casting practice such that, on metal solidification, the carbide sheet is firmly attached to the casting surface.
2086~68 While the invention has been described in terms of various preferred embodiments, the skilled artisan will appreciate the various modifications, substitutions, omissions, and changes which may be made without departing from the spirit thereof. Accordingly, it is intended that the scope of the S present invention be defined solely by the scope of the following claims including equivalents thereof.
The present invention relates to a process for the impregnation of a metal product with a surface comprising a hard wear-resistant material.
A wide variety of techniques are known for the impregnation of metals, e.g., iron, with a hard wear-resistant surface. Such techniques include flame spray coating and plasma spray coating. However, each of these spray coating techniques suffer from problems associated with the ~p~lling of surface layers during the coating process and during service as well as the particularly large expense associated with the use of this technique.
Cast-in-carbides are also known in which carbide particulates are placed in a mold and molten iron is then cast. See, for example, the discussion within U.S. Patent No. 4,119,459 to Eckmar et al. It is difficult, however, with such castings to accurately maintain the carbide particles in the desired location and in a regular distribution pattern.
In addition, certain cast-on hard surfacing techniques for use with polystyrene patterns are also known in the art. See, for example, the discussion in Hansen et al., "Application of Cast-On Ferrochrome-Based Hard Surfacing to Polystyrene Pattern C~ting~," Bureau of Mines Report of Investigations 8942, U.S. Department of the Interior, 1985.
However, this process suffers from problems associated with the low reliability of the bond formed between the wear-resistant layer, e.g., tungsten carbide, and the foam pattern. Because of this failure, the iron may 208686~
not penetrate the layer before the iron solidifies and thus, instead of impregnating the iron, the carbide spalls off the product.
The inventor of the present invention has also been involved in inventing other processes in an attempt to more effectively impregnate the 5 surface of a metal, e.g., iron, with hard phases during the casting process.
For example, attention is directed toward U.S. Patent No. 5,027,878 to Revankar et al which relates to the carbide impregnation of cast iron using evdpoldtive pattern c~ctingC (EPC) as well as U.S. Application Serial Numbers 564,184 and 564,185 which relate to the i~"plegnation of cast iron 10 and aluminum alloy castings with carbides using sand cores.
However, despite their effectiveness, these methods also have certain drawbacks. For example, the EPC method may involve the inct~ tion of special equipment in a conventional foundry. Furthermore, c~ctin~c produced by this process can suffer from distortion due to the distortion of 15 the plastic foam replicas. On the other hand, the above sand core methods of casting carbides can involve the preparation of carbide spheres which adds to the cost of the process. The cost can be further increased if a substantially flat wear-resistant surface is desired because in such a case, a surface layer equal in thickness to half the sphere ~ met~r or more will need 20 to be machined off.
Accordingly, the need still exists for a method of impregn~ting metal surfaces, and in particular iron surfaces with a hard wear-resistant material which is capable of overcoming the problems associated with known techniques.
SUMMARY OF THE INVENTION
In one aspect of the present invention, there is disclosed a method for impregnating a metal product with a hard wear-resistant material surface layer which involves the use of "pins" or "hooks" made from the wear-resistant material and which enable the wear-resistant material surface layer to be "mechanically" attached to the casting surface.
In one aspect, the present invention relates to a method for impregnating a metal product with a hard wear-resistant surface layer comprising:
(a) providing a wear-resistant layer in the form of a sintered sheet having at least one pin integrally attached onto the surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt, which metal does not metallurgically react with the wear-resistant layer, so as to produce a metal product having a wear-resistant metal surface layer, wherein at least one pin, upon casting, forms a mechanical bond between the wear-resistant layer and the coating surface.
In another aspect, the present invention relates to the product produced by this method.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a sintered carbide sheet containing four carbide "pins" according to the present invention.
-3a-Fig. 2 illustrates suitable shapes for the carbide pins which are employed in the present invention.
Fig. 3 is a photograph illustrating a ductile iron casting showing a carbide sheet having a "hook" or "pin" forming an integral part of the sheet.
s DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention can be employed for casting virtually any type of metal which is known within the art. However, cast iron, and in particular, ductile or grey iron are plefelled. Other examples of suitable metals include non-ferrous alloys and superalloys.
In the present invention, an initial step involves the formation of a sheet comprising a wear-resistant material. As to the choice of the hard wear-resistant material, the present invention can effectively employ any of the hard phases which can be sintered, such as tungsten carbide, chromium carbide, and the like. Furthermore, this wear-resistant material can include a metallic binder, such as those of the Fe group, preferably Co for use with ngsten carbide, or Ni for chromium carbide, and the like. For example, where ductile iron is employed as the metal to be cast, particles composing tllng~ten carbide with 14-17 weight ~ cobalt is preferred.
The sheet is formed by mixing a powder of the hard wear-resistant material (optionally containing a metallic binder) with a suitable organic binder, for example, a 10% polyvinyl alcohol (PVA) solution, and a suitable plasticizer, for example, 2-ethylhexyl diphenyl phosphate, phosphate ester plasticizer (e.g., KRONITEX 3600 of FMC Corporation) or a mixture of plasticizers so as to form a slip which has appro~liate rheological characteristics such that it can be formed into a sheet. In this regard, suitable binders and/or plasticizers include any which can be effectively S employed with the particular wear-resistant material.
In this process, fine particles of the wear resistant material are preferably employed, i.e., -140/200 and finer mesh size.
The outer surface of the sheet is then preferably patterned into a texture which allows for better impregnation into the iron. The shape of the 10 pattern within the sheet is any pattern which will effectively prevent the lateral movement of the sheet from component surface during use, i.e., to allow it to resist any shear force that may be applied tangentially to the sheet surface. For example, in one embodiment, a "waMe" texture is patterned onto the outer surface of the sheet. See, for example, Fig. 1.
Moreover, this pattern can be formed by any suitable means, for example, by pressing a die with the required pattern onto the surface of the sheet while the sheet is still green and in the plastic state.
The same wear-resistant material/organic binder/plasticizer mixture employed in producing the sheet is also preferably employed in forming the 20 "pins" or "hooks" which are to be attached to the sheets. The shape of these "pins" or "hooks" is any shape which allows it to "mechanically" hold the wear-resistant material sheet onto the casting surface. Two examples of suitable pin shapes are illustMted by Fig. 2. Other pin shapes can include, e.g., flat "sheets" of carbides, also having a waMe surface texture.
These pins are cast separately and then dried, e.g., in an oven at, e.g., 100~C so as to become a "rigid" solid. These pins are planted onto the 5 sheet and in particular, onto the side of the sheet containing the pattern so as to forrn the wear-resistant layer. See, for example, the arrangement illustrated in Fig. 1.
The number of pins which need to be attached to the sheet is that n~eS~ry to overcome the force of separation that may be applied to the 10 sheet surface. For example, in the embodiment illustMted by Fig. 1, four hooks are employed although, the number can vary from, e.g., 1-8 pins.
These pins can be attached after they are dried, or, they can be presintered and then attached onto the sheets. In either technique, they become an integMI part of the sheets when the sheets themselves are sintered 15 along with the attached pins. These sheets are then heated at low ~"~pe~ res e.g., 320-340~C to partially remove organic binder and plasticizer.
This sintering of the "green" sheet occurs under conditions so as to allow the sheet and the pins to become fully dense. Suitable sintering 20 conditions are recognized in the art and include, for example, that occurring in a vacuum at 1450-1475~C for 50-75 minutes.
Re~use the composition of the pin is prefeMbly identical to that of the sheet, the sintered sheet with the hooks attached is effectively stress-free when cooled to room temperature from the sintering temperature and thus, the pins form an integral part of the sheets subsequent to sintering. See, for example, the cross-section illustrated in Fig. 3.
Though the above described method uses binder and plasticizer to 5 form sheets and pins there may be other methods which may not use these organic additives. Thus for example, the carbide powder with a suitable propo"ion of metallic binder may be directly pressed into a sheet with a flat pin in a cold die press. Such sheets may then be sintered following the same procedure as for making carbide sheets using organic binders and plasticizers 10 except, of course, that the step for removal of binder and plasticizer by heating at lower te,-,peldtures is unnecessa.y.
The sintel~d wear-resistant layer is then attached onto a suitable mold surface, e.g., a sand core by means which are recognized within the art.
For example, in one embodiment, a high te"~pe,ature adhesive is employed 15 and the layer is then heated in, e.g., an oven at 100~C so as to drive moisture from the adhesive and cure it.
By high te",pe,dture, it is meant that the adhesive has a melting point higher than the metal pouring temperature. Any suitable adhesive can be employed within the present invention with high temperature inorganic 20 adhesive being p-ef~ d.
In the preferred embodiment employing ductile iron as the metal, the binder comprises a high temperature ceramic adhesive, AREMCO's Ceramabond 569, which is a proprietary high temperature binder that includes oxides of aluminum, silicon and potassium, as a colloidal sllspen~ion in water and which has a maximum use temperature of about 1650~C (Ceramabond is a trademark of AREMCO Products, Inc.).
At this point, the liquid metal is cast around the hard wear-resistant 5 layer using any of the casting techniques traditionally employed in the art, e.g., gravity feed casting, squeeze casting, vacuum casting or the like.
However, due to the ease of use, the gravity feed of metal is p-efelled. An exemplary ductile iron casting with tungsten carbide impregnation is illustrated in Fig. 3.
The method according to the present invention can be used to produce metal products which have a wide variety of applications. Furthermore, as discu~ce~ above, this process may be applied to a variety of metals and alloys thereof because the process does not require that the metal react metallurgically with the wear-resistant material sheet. However, in the 15 specific case of cast iron, there is found a metallurgical reaction which further strengthens iron-carbide bonding. This reaction can be facilitated by the waMe pattern on the sheet.
Moreover, the process of the present invention can provide these products at a greatly reduced cost when compared with prior art systems. In 20 particular, the surface modification can be effectively accomplished during the casting process without requiring any subsequent brazing or welding and without requiring additional casting facilities such as that associated with the 20~6868 EPC system. In fact, this process can be easily adapted to existing sand casting foundry practices.
In order to further illustrate the present invention and the advantages associated therewith, the following specific example is given, it being 5 understood that same is intended only as illustrated and in no wise limitative.
20~6868 Example Fine tungsten carbide/14-17% cobalt powder (-140~200 or finer mesh size) is mixed with a suitable binder such as a 10% aqueous polyvinyl alcohol solution and a suitable plasticizer (2-ethylhexyl diphenyl phosphate or S KRONITEX 3600 of FMC Corporation) or a mixture of plasticizers to form a slip with appl~liate rheological characteristics so it can be cast or rolled into a sheet. The sheet surface is patterned into a "waMe" texture as shown in Fig. 1, before the sheets become rigid through drying or curing.
Using the same carbide/binder/plasticizer mixture, pins of a suitable 10 shape (see Fig. 2) are cast separately and are dried in an oven at 100~C
when they become rigid solids. These pins are planted into the above carbide sheets on the waffle pattern side of the sheet as shown in Fig. 1, while the sheets are still plastic, i.e., before the binder resin hardens. The green carbide sheets are then sintered in vacuum at 1460~C for 60 minutes 15 when the sheet and the pins become fully dense. See Figure 3.
The sintered carbide sheet is then attached to a sand core using Aremco's Ceramabond 569 and the core/sheet is heated in an oven at 100~C
to drive out the moisture from the binder and cure it. It may also be dried at room te,l,pe,dture provided sufficiently long curing time is allowed. The 20 cast iron is cast around the sheet using the conventional casting practice such that, on metal solidification, the carbide sheet is firmly attached to the casting surface.
2086~68 While the invention has been described in terms of various preferred embodiments, the skilled artisan will appreciate the various modifications, substitutions, omissions, and changes which may be made without departing from the spirit thereof. Accordingly, it is intended that the scope of the S present invention be defined solely by the scope of the following claims including equivalents thereof.
Claims (19)
1. A method for impregnating a metal product with a hard wear-resistant surface layer comprising:
(a) providing a wear-resistant layer in the form of a sintered sheet having both a waffle pattern and a plurality of pins on a surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt which metal metallurgically reacts with the wear-resistant material so as to produce a metal product having a wear-resistant material surface layer, wherein the pins are integrally attached to the wear-resistant layer prior to casting, and upon casting, forms a mechanical bond between the wear-resistant layer and the casting surface.
(a) providing a wear-resistant layer in the form of a sintered sheet having both a waffle pattern and a plurality of pins on a surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt which metal metallurgically reacts with the wear-resistant material so as to produce a metal product having a wear-resistant material surface layer, wherein the pins are integrally attached to the wear-resistant layer prior to casting, and upon casting, forms a mechanical bond between the wear-resistant layer and the casting surface.
2. The method according to Claim 1 wherein unsintered pins are attached to the sheet and the sheet is then sintered.
3. The method according to Claim 1 wherein sintered pins are attached to the sheet and the sheet is then sintered.
4. The method according to Claims 1, 2 or 3 wherein the mold surface is a sand core and the wear-resistant layer is attached to the sand core using a high temperature adhesive.
5. The method according to Claim 4 wherein the high temperature adhesive comprises a high temperature ceramic adhesive.
6. The method according to Claims 1, 2, 3 or 5 wherein the metal comprises iron.
7. The method according to Claim 6 wherein the iron is ductile iron.
8. The method according to Claim 1, 2, 3, 5 or 7 wherein the hard wear-resistant material comprises tungsten carbide or chromium carbide, and optionally, a metallic binder.
9. The method according to Claim 8 wherein the tungsten carbide includes 14-17 weight percent cobalt.
10. The method according to Claim 1, 2, 3, 5 or 7 wherein the sheet, and optionally the pin(s), are formed from a mixture of a powder of the wear-resistant material, an organic binder, and at least one plasticizer.
11. The method according to Claim 1, 2, 3 or 5 wherein the mold surface is a sand core, the metal comprises iron and the sheet and pins are formed from a mixture of a carbide powder, and organic binder, and at least one plasticizer.
12. A method for impregnating a metal product with a hard wear-resistant surface layer comprising:
(a) providing a wear-resistant layer in the form of a sintered sheet having at least one pin integrally attached onto the surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt, which metal does not metallurgically react with the wear-resistant layer, so as to produce a metal product having a wear-resistant metal surface layer, wherein at least one pin, upon casting, forms a mechanical bond between the wear-resistant layer and the coating surface.
(a) providing a wear-resistant layer in the form of a sintered sheet having at least one pin integrally attached onto the surface thereof;
(b) attaching the wear-resistant layer to a mold surface; and (c) casting a metal melt, which metal does not metallurgically react with the wear-resistant layer, so as to produce a metal product having a wear-resistant metal surface layer, wherein at least one pin, upon casting, forms a mechanical bond between the wear-resistant layer and the coating surface.
13. The method according to claim 12 wherein the wear-resistant layer has a waffle pattern on the surface to which the at least one pin is attached.
14. The method according to claim 12 wherein the sheet has a plurality of pins integrally attached hereto.
15. The method according to claim 12, 13 or 14 wherein the mold surface is a sand core and the wear-resistant layer is attached to the sand core using a high temperature adhesive.
16. The method according to Claim 12, 13 or 14 wherein the sheet, and optionally the pins, are formed from a mixture of powder of the wear-resistant material, and organic binder, and at least one plasticizer.
17. The method according to Claim 8 wherein the hard wear-resistant material further comprises a metallic binder.
18. The method according to Claim 10 wherein the pins are formed from a mixture of a powder of the wear-resistant material, an organic binder, and at least one plasticizer.
19. The method according to Claim 16 wherein the pins are formed from a mixture of powder of the wear-resistant material, and organic binder, and at least one plasticizer.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/822,904 US5267600A (en) | 1992-01-21 | 1992-01-21 | Hard facing casting surfaces with wear-resistant sheets |
US822,904 | 1992-01-21 |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2086868A1 CA2086868A1 (en) | 1993-07-22 |
CA2086868C true CA2086868C (en) | 1998-07-21 |
Family
ID=25237297
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002086868A Expired - Lifetime CA2086868C (en) | 1992-01-21 | 1993-01-07 | Hard facing casting surfaces with wear-resistant sheets |
Country Status (6)
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US (3) | US5267600A (en) |
EP (1) | EP0554682B1 (en) |
JP (1) | JPH0798262B2 (en) |
CA (1) | CA2086868C (en) |
DE (1) | DE59304769D1 (en) |
MX (1) | MX9300127A (en) |
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US9616951B2 (en) | 2002-03-06 | 2017-04-11 | Deere & Company | Non-carburized components of track-type machines having a metallurgically bonded coating |
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US9003681B2 (en) * | 2006-09-18 | 2015-04-14 | Deere & Company | Bucket teeth having a metallurgically bonded coating and methods of making bucket teeth |
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US9283621B2 (en) | 2012-06-21 | 2016-03-15 | Deere & Company | Method for forming a composite article |
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-
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-
1993
- 1993-01-07 CA CA002086868A patent/CA2086868C/en not_active Expired - Lifetime
- 1993-01-12 MX MX9300127A patent/MX9300127A/en unknown
- 1993-01-14 EP EP93100454A patent/EP0554682B1/en not_active Expired - Lifetime
- 1993-01-14 DE DE59304769T patent/DE59304769D1/en not_active Expired - Lifetime
- 1993-01-21 JP JP5026224A patent/JPH0798262B2/en not_active Expired - Lifetime
- 1993-04-29 US US08/053,697 patent/US5383513A/en not_active Expired - Lifetime
- 1993-08-27 US US08/112,530 patent/US5443916A/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
US5267600A (en) | 1993-12-07 |
CA2086868A1 (en) | 1993-07-22 |
EP0554682B1 (en) | 1996-12-18 |
US5443916A (en) | 1995-08-22 |
JPH0798262B2 (en) | 1995-10-25 |
JPH05261515A (en) | 1993-10-12 |
EP0554682A1 (en) | 1993-08-11 |
US5383513A (en) | 1995-01-24 |
MX9300127A (en) | 1993-07-01 |
DE59304769D1 (en) | 1997-01-30 |
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