CA1140947A - Spraying material for hot or plasma spraying and a process of its production - Google Patents
Spraying material for hot or plasma spraying and a process of its productionInfo
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- CA1140947A CA1140947A CA000349043A CA349043A CA1140947A CA 1140947 A CA1140947 A CA 1140947A CA 000349043 A CA000349043 A CA 000349043A CA 349043 A CA349043 A CA 349043A CA 1140947 A CA1140947 A CA 1140947A
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Abstract
ABSTRACT OF THE DISCLOSURE:
Spraying material for hot or plasma spraying consisting of several metal oxides from which at least one oxide is a glass-forming oxide characterized by that it is formed by agglomerates of at least two fundamental oxides, especially Al2O3, MgO, CaO, BaO, Cr2O3, TiO2 or ZrO2 in the amount 50 to 99 % by weight and by at least one glass-forming oxide with the melting point lower about 50 to 1100°C than the melting points of fundamental oxides, especially SiO2, in the amount 1 to 50 % by weight. And a process for the production of such a spraying material.
Spraying material for hot or plasma spraying consisting of several metal oxides from which at least one oxide is a glass-forming oxide characterized by that it is formed by agglomerates of at least two fundamental oxides, especially Al2O3, MgO, CaO, BaO, Cr2O3, TiO2 or ZrO2 in the amount 50 to 99 % by weight and by at least one glass-forming oxide with the melting point lower about 50 to 1100°C than the melting points of fundamental oxides, especially SiO2, in the amount 1 to 50 % by weight. And a process for the production of such a spraying material.
Description
The invention relates to a material for hot or plasma spraying especially non-metallic refractory material suitable for the formation of resistant coating sand to a process of the production of such a material as well.
At present miscellaneous metallic and non-metallic materials are known and for the produciton of protective coatings are used; composition of the materials is varied according to required properties of the coating regarding as chemical composition of starting materials as their physical properties. It deals with materials exhibiting required properties especially refractoriness, abrasive wear resistance, minimum porosity, good holding on subjacent material and resistance to mechanical and thermal impacts as well as chem-ical resistance to the influence of surrounding medium, the problem still remains in reaching complexity of these proper-ties in one spraying.
For example metallic especially noble deficient materials as chromium, titanium, nickel and similar, even refined with another additives or alloy additions, if necessary, are used with these materials, as it follows from properties of their starting components, very good mechanical properties of the resulting coating are achieved but heat resistance or chemical resistance of coatiny thus made is usually substantially worse.
Another large group of spraying materials are non-metallic materials especially those based on oxide ceramics where spraying material is made up either from one oxide or from a mixture of several oxides in proper ratio. Typical representatives of these materials are materials on the basis of aluminium oxide A12O3 whose characteristic feature is com-position of the coating from a mixture of gamma and alphaA12O3 modification. At temperatures above 1180C irreversible 1:14~47 modification transformation of the A12O3 gamma modification to the alpha modification takes place at the same time what is accompanied with permanent contraction and increase of volume weight. Coatings on the basis A12O3, the so-called corundum coatings are characterized by extraordinary abrasive wear resistance, high adhesion to subjacent material and by very good electric properties, their corrosion resistance is however lower as a result of open porosity, which amonts 6 to 8 ~ and after transformation to alpha modification it increases to 9 to 10 %. Coatings on the basis of zirconium oxide ZrO2 have especially excellent heat insulating properties, layers made from chromium oside Cr2O are very hard and abrasive wear resistant, coatings of titanium oxide Tio2 are compact and well machinable and there are very hard for example layers of hafnium oxide HfO2; common disadvantage of these one-component ~praying materials is however relatively high porosity and from it resulting smaller resistance ~o influences of aggres-sive media.
This disadvantage is partially overcome by coatings on the basis of silicium oxide SiO2 which forms compact coating with very small coefficient of thermal expansion and with zero porosity. This coating is considerably resistant to corrosion and sudden temperature changes, on the other hand its resis-tance to mechanical impacts is however entirely insufficient.
The problem of improving properties of plasma coatings was lately solved by formation of mixture of several oxides exhibiting in proper ratio more convenient properties than the properties of basic components are. It is for example zirconium silicate ZrSiO4 at which in coating composition ZrO2 prevails in volume stable tetragonal modification in homogenous mixture with SiO2 in glass form. At temperatures - 1140~47 above 1150C zircon is reversely synthetized. The coating has excellent resistance to temperature changes, a good heat insulating power and it very well resists to corrosion by melted glass materials, slags and by colored metals due to poor wetting of zircon by the above-ment-ioned melts. The general corrosion resistance is however negatively influenced by that open porosity of coating is 15 to 25 % in spite oE
presence of glass form of SiO2.
From further multicomponent spraying materials for example magnesia spinel MgA1204 can be presented; it has low porosity, high electrical resistance and excellent adhesion to subjacent material but its corrosion resistance is already substantially lower. There are also very spread multicomponent spraying materials on the basis of A1203 with additives of TiO2 or Cr203 where TiO2 addition increases especially compactness of th0 coating at simultaneous improvement of resistance to tem-perature changes and Cr203 addition ensures better abrasive wear resistance however other disadvantages are not in1uenced.
Finally it is known also the use of A1203 with addition of SiO2. This spraying material retains very good mechanical properties of corundum coatings the presence of SiO2 enhallcing also corrosion resistance. With regard to the mechanism oE
transfGrmation of gamma and alpha A1203 modifications however not even here as a result of the negative influencing of resulting coating porosity can be reached corrosion resistance comparable with protective SiO2 layers what is at simultaneous achieving oE hiyh reEractorincss, abrasivc wear and suddcn temperature chan~es resistance the main object of this inven-tion.
Further possible way how to lower porosity of the per-formed coating and thus increase corrosion resistance is a -~ 114~)947 choice of proper granulation of starting spraying material or use of amorphous additive as for example æinc by what hardness ` and heat resistance of the coating becomes however again worse. Known two~component coatings with amorphous additive besides it do not make possible sufficient adaptation of the resistance to corrosion medium of given composition.
With respect to a process of the production of spraying material for hot or plasma spraying there are use altogether traditional ways of the treatment by melting of starting materials or their mixtures in arc furnaces and by subsequent treatment on granularity and the shape proper for the applica-tion by plasma burner. These processes are considerably uneconomical with respect to relatively s~lall treated amounts of material especially with respect to high melting temperatures of usual spraying materials. Besides it at the treatment of materials alloyed with small amounts of additives to very small grains of the size usual at the spraying by plasma stream there are already revealed the heterogeneities in the structure of material negatively influencing the quality of the per-formed coatings.
It is known as well a substanitally power-consuming alloying of spraying materials by diffusion of corresponding additives under high temperatures or granulation of the mix-ture of grains of individual components proper only or the production of spraying materials consisting of two or more fundamental components contained in the mixture in relatively high weight ratio. It is known a process as well where the relatively large grains of one or more components are enve-loped by very fine additives with the grain size smaller than 0.3 micrometer. However not even these processes comply with the requirement of high homogenity of spraying material.
The above drawbacks of prior art spraying materials for hot or plasma spraying are overcome by a spraying material f consisting of several metal oxides of which at least one oxide is a glass-forming oxide, said spraying material being characterized in thàt it is formed of at least two fundamental oxides in the amount 50 to 99~ by weight, and by at least one glass-forming oxide with the melting point lower about 50 to 1100C than the melting points of said fundamental oxides in the amount 1 to 50~ by weight.
In particular the present invention provides a spraying material suitable for hot or plasma spraying consisting essentially of a plurality o~ metal oxides of which at least one oxide is a glass-formint oxide, characterized by being formed of (a) two or more fundamental oxides selected from the group consisting o A12O3, MgO, CaO, BaO, Cr2o3, TiO2 and ~rO2 in an amount of 50 to 99%
by weight and (b) one or more glass forming oxides having a melt-ing point 50C to 1100C lower than the melting points of said fundamental oxides, in an amount of 1% to 50% by weight, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass forming oxides having a particle size of 0.0002 to 0.04 mm.
The glass forming oxide may, for example, be SiO2.
Spraying material can preferably contain agglomerates 50 to 80~ by weight CaO, 1 to 5~ by welght MgO, and 18 to 45~
by weight SiO2, or 50 to 90% by weight MgO, 1 to 5% by weight CaO, and 5 to 45% by weight SiO2, or 90 to 95% by weight Cr2o3, 2 to 8% by weight TiO2, and 1 to 3% by weight SiO2, or 65 to 75% by weight Cr2O3, 20 to 30% by weight MgO, and 2 to ll~V947 10% by weight SiO2, or 30 to 40% by weight Al2O3, 15 to 25%
by weight CaO, and 35 to 50% by weight SiO2, or 25 to 30% by weight A12O3, 40 to 45~ by weight BaO, and 25 to 35~ by weight SiO2, or 46 to 51~ by weight A12O3, 33 to 41% by weight ZrO2, and 8 to 21% by weight SiO2, or 25 to 30~ by weight A12O3, 25 to 30% by weight Cr2o3, 25 to 30% by weight ZrO2, and 10 to 25% by weight SiO2.
The above mentioned drawbacks of prior art processes of the production of spraying materials for hot or plasma spraying consisting of several metal oxides from which at least one oxide is a glass-forming oxide are overcome by the process according to the invention characterized in that fundamental oxides and said glass-forming oxide or oxides are brought separately or in a previously prepared mixture into a suitably stabllized plasma stream with a concentration of charged partlcles between 2.00 x 1024 and 0.3 x 1023, for example into a water stabillzed plasma stream,they are partially melted or melted-down and the resulting agglomerates are captured or recove~ed for example by water or air screen.
The fundamental oxidescan have a particle size of 0.01 to 0.2 mm and the glass oxide or oxides can have a particle size of 0.0002 to 0.04 mm.
The process according to the invention can be preferably carried out so that into the plasma stream is brought a mixture of fundamental oxides with particle size 0.01 to 0.2 mm and glass-forming oxide or oxides with particle size 0.0002 to 0,04 mm, particles of fundamental oxides being surface melted and particles of glass-forming oxide or oxides being melted-down or so that fundamental oxides and glass-forming oxide or oxides are brought separately or in advance prepared mixture into the plasma stream with concentration of charged particles between 2.00 x 1024 and 0.3 x 1023, 114~)947 especially into water stabilized plasma, they are partially melted or melted-down ànd partially melted or melted-down are put directly on the surface which is to be protected by the coating.
The subject matter of the invention is further elucidated in several examples of concrete embodiment.
Example 1 Into the plasma stream of water stabilized plasma burner adapted for spraying of powdered materials is brought a mixture of 65% by weight of powdered CaO with particle size 0.04 to 0.06 mm, 3% by weight of MgO with the same size, and 32% by weight of SiO2 with particle size 0.0005 to 0.0008 mm, individual particles are exposed to temperature between 15 000 and 60 000C and after relevant reactions took place they are captured by water screen. Resulting agglomerates are formed predominantly by dlcalciumsllicate accompanied wlth small amount of montlcelllte as a bindlng phase and with smaller amount of glass phase~
~14~)947 Example 2 Into the plasma stream are brought 70 % by weight of MgO
and 2 % by weight of CaO in a mixture with 28 % by weight of SiO2 under conditions analogous as in the preceding example.
Materials are put on the surface o preheated constructional component and they are let to cool slowly. Resulting material of the coating will be formed by forsterite accompanied with small àmount of periclase, monticellite and of glass phase.
Example 3 For spraying carried out under condiditons analogous to the preceding example 95 % by weight of Cr2O3, 3 % by weight of TiO2, and 2 % by weight of SiO2 are used. Resulting mate-rial will be formed mostly by eskolaite and by small amount of glass phase.
Example 4 70 % by weight of Cr2O3, 25 % by weight of MgO, and 5 %
by weight of SiO2 are used. Resulting material will be mostly formed by chrompicotite accompanied with small amount of for-sterite and of glass phase.
Example 5 36 % by weight of A12O3, 20 % by weight of CaO, and 44 by weight of SiO2 are used. Substantial part of resulting material will be forrned by anorthite accompanied with glass phase.
Example 6 27 % by weight of A12O3, 41 '~ by weight of ~aO, and 32 %
by weight of SiO2 are used. Resulting material will be mostly formed by celsian accompanied with glass phase.
Example 7 46 to 51 % by weight of A12O3, 33 to 41 % by weight oE
ZrO2, and 12 to 16 % by weight of SiO2 are used. ~esulting 114~947 material will be mostl~ formed by corundum accompanied with baddeleyite, mullite and glass phase.
~xample 8
At present miscellaneous metallic and non-metallic materials are known and for the produciton of protective coatings are used; composition of the materials is varied according to required properties of the coating regarding as chemical composition of starting materials as their physical properties. It deals with materials exhibiting required properties especially refractoriness, abrasive wear resistance, minimum porosity, good holding on subjacent material and resistance to mechanical and thermal impacts as well as chem-ical resistance to the influence of surrounding medium, the problem still remains in reaching complexity of these proper-ties in one spraying.
For example metallic especially noble deficient materials as chromium, titanium, nickel and similar, even refined with another additives or alloy additions, if necessary, are used with these materials, as it follows from properties of their starting components, very good mechanical properties of the resulting coating are achieved but heat resistance or chemical resistance of coatiny thus made is usually substantially worse.
Another large group of spraying materials are non-metallic materials especially those based on oxide ceramics where spraying material is made up either from one oxide or from a mixture of several oxides in proper ratio. Typical representatives of these materials are materials on the basis of aluminium oxide A12O3 whose characteristic feature is com-position of the coating from a mixture of gamma and alphaA12O3 modification. At temperatures above 1180C irreversible 1:14~47 modification transformation of the A12O3 gamma modification to the alpha modification takes place at the same time what is accompanied with permanent contraction and increase of volume weight. Coatings on the basis A12O3, the so-called corundum coatings are characterized by extraordinary abrasive wear resistance, high adhesion to subjacent material and by very good electric properties, their corrosion resistance is however lower as a result of open porosity, which amonts 6 to 8 ~ and after transformation to alpha modification it increases to 9 to 10 %. Coatings on the basis of zirconium oxide ZrO2 have especially excellent heat insulating properties, layers made from chromium oside Cr2O are very hard and abrasive wear resistant, coatings of titanium oxide Tio2 are compact and well machinable and there are very hard for example layers of hafnium oxide HfO2; common disadvantage of these one-component ~praying materials is however relatively high porosity and from it resulting smaller resistance ~o influences of aggres-sive media.
This disadvantage is partially overcome by coatings on the basis of silicium oxide SiO2 which forms compact coating with very small coefficient of thermal expansion and with zero porosity. This coating is considerably resistant to corrosion and sudden temperature changes, on the other hand its resis-tance to mechanical impacts is however entirely insufficient.
The problem of improving properties of plasma coatings was lately solved by formation of mixture of several oxides exhibiting in proper ratio more convenient properties than the properties of basic components are. It is for example zirconium silicate ZrSiO4 at which in coating composition ZrO2 prevails in volume stable tetragonal modification in homogenous mixture with SiO2 in glass form. At temperatures - 1140~47 above 1150C zircon is reversely synthetized. The coating has excellent resistance to temperature changes, a good heat insulating power and it very well resists to corrosion by melted glass materials, slags and by colored metals due to poor wetting of zircon by the above-ment-ioned melts. The general corrosion resistance is however negatively influenced by that open porosity of coating is 15 to 25 % in spite oE
presence of glass form of SiO2.
From further multicomponent spraying materials for example magnesia spinel MgA1204 can be presented; it has low porosity, high electrical resistance and excellent adhesion to subjacent material but its corrosion resistance is already substantially lower. There are also very spread multicomponent spraying materials on the basis of A1203 with additives of TiO2 or Cr203 where TiO2 addition increases especially compactness of th0 coating at simultaneous improvement of resistance to tem-perature changes and Cr203 addition ensures better abrasive wear resistance however other disadvantages are not in1uenced.
Finally it is known also the use of A1203 with addition of SiO2. This spraying material retains very good mechanical properties of corundum coatings the presence of SiO2 enhallcing also corrosion resistance. With regard to the mechanism oE
transfGrmation of gamma and alpha A1203 modifications however not even here as a result of the negative influencing of resulting coating porosity can be reached corrosion resistance comparable with protective SiO2 layers what is at simultaneous achieving oE hiyh reEractorincss, abrasivc wear and suddcn temperature chan~es resistance the main object of this inven-tion.
Further possible way how to lower porosity of the per-formed coating and thus increase corrosion resistance is a -~ 114~)947 choice of proper granulation of starting spraying material or use of amorphous additive as for example æinc by what hardness ` and heat resistance of the coating becomes however again worse. Known two~component coatings with amorphous additive besides it do not make possible sufficient adaptation of the resistance to corrosion medium of given composition.
With respect to a process of the production of spraying material for hot or plasma spraying there are use altogether traditional ways of the treatment by melting of starting materials or their mixtures in arc furnaces and by subsequent treatment on granularity and the shape proper for the applica-tion by plasma burner. These processes are considerably uneconomical with respect to relatively s~lall treated amounts of material especially with respect to high melting temperatures of usual spraying materials. Besides it at the treatment of materials alloyed with small amounts of additives to very small grains of the size usual at the spraying by plasma stream there are already revealed the heterogeneities in the structure of material negatively influencing the quality of the per-formed coatings.
It is known as well a substanitally power-consuming alloying of spraying materials by diffusion of corresponding additives under high temperatures or granulation of the mix-ture of grains of individual components proper only or the production of spraying materials consisting of two or more fundamental components contained in the mixture in relatively high weight ratio. It is known a process as well where the relatively large grains of one or more components are enve-loped by very fine additives with the grain size smaller than 0.3 micrometer. However not even these processes comply with the requirement of high homogenity of spraying material.
The above drawbacks of prior art spraying materials for hot or plasma spraying are overcome by a spraying material f consisting of several metal oxides of which at least one oxide is a glass-forming oxide, said spraying material being characterized in thàt it is formed of at least two fundamental oxides in the amount 50 to 99~ by weight, and by at least one glass-forming oxide with the melting point lower about 50 to 1100C than the melting points of said fundamental oxides in the amount 1 to 50~ by weight.
In particular the present invention provides a spraying material suitable for hot or plasma spraying consisting essentially of a plurality o~ metal oxides of which at least one oxide is a glass-formint oxide, characterized by being formed of (a) two or more fundamental oxides selected from the group consisting o A12O3, MgO, CaO, BaO, Cr2o3, TiO2 and ~rO2 in an amount of 50 to 99%
by weight and (b) one or more glass forming oxides having a melt-ing point 50C to 1100C lower than the melting points of said fundamental oxides, in an amount of 1% to 50% by weight, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass forming oxides having a particle size of 0.0002 to 0.04 mm.
The glass forming oxide may, for example, be SiO2.
Spraying material can preferably contain agglomerates 50 to 80~ by weight CaO, 1 to 5~ by welght MgO, and 18 to 45~
by weight SiO2, or 50 to 90% by weight MgO, 1 to 5% by weight CaO, and 5 to 45% by weight SiO2, or 90 to 95% by weight Cr2o3, 2 to 8% by weight TiO2, and 1 to 3% by weight SiO2, or 65 to 75% by weight Cr2O3, 20 to 30% by weight MgO, and 2 to ll~V947 10% by weight SiO2, or 30 to 40% by weight Al2O3, 15 to 25%
by weight CaO, and 35 to 50% by weight SiO2, or 25 to 30% by weight A12O3, 40 to 45~ by weight BaO, and 25 to 35~ by weight SiO2, or 46 to 51~ by weight A12O3, 33 to 41% by weight ZrO2, and 8 to 21% by weight SiO2, or 25 to 30~ by weight A12O3, 25 to 30% by weight Cr2o3, 25 to 30% by weight ZrO2, and 10 to 25% by weight SiO2.
The above mentioned drawbacks of prior art processes of the production of spraying materials for hot or plasma spraying consisting of several metal oxides from which at least one oxide is a glass-forming oxide are overcome by the process according to the invention characterized in that fundamental oxides and said glass-forming oxide or oxides are brought separately or in a previously prepared mixture into a suitably stabllized plasma stream with a concentration of charged partlcles between 2.00 x 1024 and 0.3 x 1023, for example into a water stabillzed plasma stream,they are partially melted or melted-down and the resulting agglomerates are captured or recove~ed for example by water or air screen.
The fundamental oxidescan have a particle size of 0.01 to 0.2 mm and the glass oxide or oxides can have a particle size of 0.0002 to 0.04 mm.
The process according to the invention can be preferably carried out so that into the plasma stream is brought a mixture of fundamental oxides with particle size 0.01 to 0.2 mm and glass-forming oxide or oxides with particle size 0.0002 to 0,04 mm, particles of fundamental oxides being surface melted and particles of glass-forming oxide or oxides being melted-down or so that fundamental oxides and glass-forming oxide or oxides are brought separately or in advance prepared mixture into the plasma stream with concentration of charged particles between 2.00 x 1024 and 0.3 x 1023, 114~)947 especially into water stabilized plasma, they are partially melted or melted-down ànd partially melted or melted-down are put directly on the surface which is to be protected by the coating.
The subject matter of the invention is further elucidated in several examples of concrete embodiment.
Example 1 Into the plasma stream of water stabilized plasma burner adapted for spraying of powdered materials is brought a mixture of 65% by weight of powdered CaO with particle size 0.04 to 0.06 mm, 3% by weight of MgO with the same size, and 32% by weight of SiO2 with particle size 0.0005 to 0.0008 mm, individual particles are exposed to temperature between 15 000 and 60 000C and after relevant reactions took place they are captured by water screen. Resulting agglomerates are formed predominantly by dlcalciumsllicate accompanied wlth small amount of montlcelllte as a bindlng phase and with smaller amount of glass phase~
~14~)947 Example 2 Into the plasma stream are brought 70 % by weight of MgO
and 2 % by weight of CaO in a mixture with 28 % by weight of SiO2 under conditions analogous as in the preceding example.
Materials are put on the surface o preheated constructional component and they are let to cool slowly. Resulting material of the coating will be formed by forsterite accompanied with small àmount of periclase, monticellite and of glass phase.
Example 3 For spraying carried out under condiditons analogous to the preceding example 95 % by weight of Cr2O3, 3 % by weight of TiO2, and 2 % by weight of SiO2 are used. Resulting mate-rial will be formed mostly by eskolaite and by small amount of glass phase.
Example 4 70 % by weight of Cr2O3, 25 % by weight of MgO, and 5 %
by weight of SiO2 are used. Resulting material will be mostly formed by chrompicotite accompanied with small amount of for-sterite and of glass phase.
Example 5 36 % by weight of A12O3, 20 % by weight of CaO, and 44 by weight of SiO2 are used. Substantial part of resulting material will be forrned by anorthite accompanied with glass phase.
Example 6 27 % by weight of A12O3, 41 '~ by weight of ~aO, and 32 %
by weight of SiO2 are used. Resulting material will be mostly formed by celsian accompanied with glass phase.
Example 7 46 to 51 % by weight of A12O3, 33 to 41 % by weight oE
ZrO2, and 12 to 16 % by weight of SiO2 are used. ~esulting 114~947 material will be mostl~ formed by corundum accompanied with baddeleyite, mullite and glass phase.
~xample 8
2~ % by weight of A12O3, 28 % by weight of Cr2O3, 28 % by weight of ZrO2, and 16 % by weight of SiO2 are used. Resulting material will consist of approximately equal parts of baddele-yite, ruby and eskolaite accompanied with smaller amount of glass phase.
The materials prepared according to the above-described examples give security o~ high refractoriness, resistance to corrosion by metallic or non-metallic melts, abrasive wear resistance and of sudden changes of temperature. It deals with new materials of proper composition and properties containing always definite amount o glass phase of SiO2 which substan-tially increases corrosion resistance of coating. Besides this glass phase there is always present also crystalline phase physical and chemical properties of which are co-decisive Eor maximum resistance of coating to corrosive medium of given composition and which is formed at least by two fundamental oxides with respect to necessity o suficiently fine choice of its properties.
~ ligh homogeneity of performed coating even at relatively small amounts o~ some additives is achieved by the capture oE
resulting agglomerates by water or air screen and by their new application using plasma burner. With very good results all mentioned spraying materials can be put directly on the sur-face which is to be protected by the coating, practically non-porous coating being obtained at conservation of very good mechanical properties by the choice o~ proper percentual con-tent and size of SiO2 particles.
_ ~ _
The materials prepared according to the above-described examples give security o~ high refractoriness, resistance to corrosion by metallic or non-metallic melts, abrasive wear resistance and of sudden changes of temperature. It deals with new materials of proper composition and properties containing always definite amount o glass phase of SiO2 which substan-tially increases corrosion resistance of coating. Besides this glass phase there is always present also crystalline phase physical and chemical properties of which are co-decisive Eor maximum resistance of coating to corrosive medium of given composition and which is formed at least by two fundamental oxides with respect to necessity o suficiently fine choice of its properties.
~ ligh homogeneity of performed coating even at relatively small amounts o~ some additives is achieved by the capture oE
resulting agglomerates by water or air screen and by their new application using plasma burner. With very good results all mentioned spraying materials can be put directly on the sur-face which is to be protected by the coating, practically non-porous coating being obtained at conservation of very good mechanical properties by the choice o~ proper percentual con-tent and size of SiO2 particles.
_ ~ _
Claims (14)
1. A spraying material suitable for hot or plasma spraying consisting essentially of a plurality of metal oxides of which at least one oxide is a glass-forming oxide, character-ized by being formed of (a) two or more fundamental oxides selected from the group consisting of Al2O3, MgO, CaO, BaO, Cr2O3, TiO2 and ZrO2 in an amount of 50 to 99%
by weight and (b) one or more glass forming oxides having a melt-ing point 50°C to 1100°C lower than the melting points of said fundamental oxides, in an amount of 1% to 50% by weight, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass forming oxides having a particle size of 0.0002 to 0.04 mm.
by weight and (b) one or more glass forming oxides having a melt-ing point 50°C to 1100°C lower than the melting points of said fundamental oxides, in an amount of 1% to 50% by weight, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass forming oxides having a particle size of 0.0002 to 0.04 mm.
2. A spraying material according to claim 1 wherein said glass forming oxide is SiO2.
3. A spraying material according to Claim 1 character-ized in that it is formed by 50 to 80% by weight of CaO, 1 to 5 by weight of MgO, and 18 to 45% by weight of SiO2.
4. A spraying material according to Claim 1 character-ized in that it is formed by 50 to 90% by weight of MgO, 1 to 5%
by weight of CaO, and 5 to 45% by weight of SiO2.
by weight of CaO, and 5 to 45% by weight of SiO2.
5. A spraying material according to Claim 1 character-ized in that it is formed by 90 to 95% by weight of Cr2O3, 2 to 8% of TiO2, and 1 to 3% by weight of SiO2.
6. A spraying material according to Claim 1, characterized in that it is formed by 65 to 75% by weight of Cr2O3, 20 to 30% by weight of MgO, and 2 to 10% by weight of SiO2.
7. A spraying material according to Claim 1,.
characterized in that it is, formed by 30 to 40% by weight of Al2O3, 15 to 25% by weight of CaO, and 35 to 50% by weight of SiO2.
characterized in that it is, formed by 30 to 40% by weight of Al2O3, 15 to 25% by weight of CaO, and 35 to 50% by weight of SiO2.
8. A spraying material according to Claim 1, characterized in that it is formed by 25 to 30% by weight of Al2O3, 40 to 45% by weight of BaO, and 25 to 35% by weight of SiO2.
9. A spraying material according to Claim 1, characterized in that it is formed by 46 to 51% by weight of Al2O3, 33 to 41% by weight of ZrO2, and 8 to 21% by weight of SiO2.
10. A spraying material according to Claim 1, characterized in that it is formed by 25 to 30% by weight of Al2O3, 25 to 30% by weight of Cr2O3, 25 to 30% by weight of ZrO2, and 10 to 25% by weight of SiO2.
11. A process of production of spraying material suitable for hot or plasma spraying consisting essentially of a plurality of metal oxides of which at least one oxide is a glass-forming oxide characterized in that fundamental oxides and said glass forming oxide or oxides are brought separately or in a previously prepared mixture into a suitably stabilized plasma stream with a concentration of char-ged particles between 2.00 x 1024 and 0.3 x 1023 per cm3 and are partially melted or melted-down, the resulting agglomerates being recovered, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass-forming oxide or oxides having a particle size or 0.0002 to 0.04 mm.
12. A process according to claim 11 wherein said plasma stream is water stabilized and said agglomerates are recovered by a water or air screen.
13. A process of production of spraying material suitable for hot or plasma spraying consisting essentially of a plurality of metal oxides of which at least one oxide is a glass-forming oxide, characterized in that fundamental oxides and said glass-forming oxide or oxides are brought separately or in a previously prepared mixture into a suitably stabilized plasma stream with a concentration of charged particles between 2.0 x 1024 and 0.3 x 1023 per cm3 and are partially melted or melted-down, said partially melted or melted-down particles being put directly on the surface which is to be protected by a coating, said fundamental oxides having a particle size of 0.01 to 0.2 mm, said glass-forming oxide or oxides having a particle size of 0.0002 to 0.04 mm.
14. A process according to Claim 13, wherein said plasma stream is a water stabilized plasma stream.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000349043A CA1140947A (en) | 1980-04-02 | 1980-04-02 | Spraying material for hot or plasma spraying and a process of its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000349043A CA1140947A (en) | 1980-04-02 | 1980-04-02 | Spraying material for hot or plasma spraying and a process of its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1140947A true CA1140947A (en) | 1983-02-08 |
Family
ID=4116621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000349043A Expired CA1140947A (en) | 1980-04-02 | 1980-04-02 | Spraying material for hot or plasma spraying and a process of its production |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1140947A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112375402A (en) * | 2020-11-27 | 2021-02-19 | 安徽盈锐优材科技有限公司 | Preparation method of novel thermal spraying chromium oxide powder |
-
1980
- 1980-04-02 CA CA000349043A patent/CA1140947A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112375402A (en) * | 2020-11-27 | 2021-02-19 | 安徽盈锐优材科技有限公司 | Preparation method of novel thermal spraying chromium oxide powder |
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