CA1044926A - Nickel-base metal-ceramic heat-resistant alloy - Google Patents
Nickel-base metal-ceramic heat-resistant alloyInfo
- Publication number
- CA1044926A CA1044926A CA229,109A CA229109A CA1044926A CA 1044926 A CA1044926 A CA 1044926A CA 229109 A CA229109 A CA 229109A CA 1044926 A CA1044926 A CA 1044926A
- Authority
- CA
- Canada
- Prior art keywords
- nickel
- turbine
- sealing
- boron nitride
- hours
- 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
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A nickel-base metal-ceramic heat-resistant sealing material, comprising, weight per cent:
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
The material has a reduced hardness ranging from 25 to 40 kg/mm2 and enhanced heat resistance and thermal stability.
The material is adapted mainly for producing sealing parts, such as, insert-pieces for turbine rotary shrouds designed to pre-clude the leakage of hot gases which could have taken place in case of increased clearances between the surface of the sealing part in the rim of the turbine shroud and rotating blades of a turbine rotor. The material is suitable for producing sealing members in the form of plates, bushes and bands useful for continuous operation over 3000 hours at 1000°C or for short-term operation at 1200°C.
A nickel-base metal-ceramic heat-resistant sealing material, comprising, weight per cent:
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
The material has a reduced hardness ranging from 25 to 40 kg/mm2 and enhanced heat resistance and thermal stability.
The material is adapted mainly for producing sealing parts, such as, insert-pieces for turbine rotary shrouds designed to pre-clude the leakage of hot gases which could have taken place in case of increased clearances between the surface of the sealing part in the rim of the turbine shroud and rotating blades of a turbine rotor. The material is suitable for producing sealing members in the form of plates, bushes and bands useful for continuous operation over 3000 hours at 1000°C or for short-term operation at 1200°C.
Description
L9 2Ç~
The present invention relates -to nickel-base metal-ceramic heat-resistant sealing materials produced by conventional powder metallurgical methods. Such rnaterials prove to be most advantageous when producing sealing memhers (parts) for such units as turbine wheel rims exposed to the effect of gas flows at high temperatures. The nickel-base materials belong to heat-resi~tant metal-ceramic materials which find use in gas turbine pumps and in certain types of surface transport ~ehicles and aircraft.
A nickel-base metal-ceramic heat-resistant material is klown comprising the following alloying elements in per cent by weigh;t: silicon, up to 3, and graphite, up to 8. The material is employed in ~.he manufacture of plates for radial and labyrinth turbine seals.llowever, at a gas flow temperature of about 1000C
these materials are not capable of providing long service life for the machines. This is attributable to the burning-out of their graphite component, through which the surface hardness of the sealing members produced from this material is enhanced with the ensuing higher wear of rotating turbine parts (turbine blades) found in contact therewith.
Moreover, this material is not suitable for producing sealing members (parts) in the form of rolled band, since graphite increases alloy brittleness.
Some nickel-base materials contain from 5 to 20 per cent by weight of silicon, copper, mica, chrom~um or boron r nitride. Such materials are capable of providing long service life of machines but a temperature not in excess of 850C. Thus, the nickel-base materials containing copper can operate, as a , rule, at a temperature not exceeding 600C. Those, comprising mica or micaceous compounds such as vermiculite in muscovite eature lower thermal stability. The materials, compxising chromium (or nichrome-base compounds with the nicke:L-to-chromium - 1- ~ i ~4~26 ratio of 4:1) and boron nitride are inapplicable in machines operating at a temperature above 850~C.
As is commonly known, boron nitride is similar in structure to graphite, bu-t in contras-t to the latter, it has a higher heat resistance and does not burn out in service.
However, the nickel-base materials, containing boron nitride, are prone to cubical oxidation by end products of fuel combustion which causes the geometry of sealing plates to be disturbed and bands in this material to he distorted duriny its usage. At a temperature of gas flows of about 1000C these materials do not provide long-term turbine operation. As the turbine blades wear out, the clearance between the turbine rotary shroud rim and its rotating blades, ~hrough which hot yases can leak, in-creases, this resulting in excessive fuel consumption, lower turbine efficiency and in a decrease in the range of operation of a flying vehicle.
Since the speed of transport vehicles is on the rise, turbine ratings increase as well, with the ensuing rise in the tempera-ture of a gas flow in such turbines. Therefore a need has arisen for providing a nickel-base material which would feature a higher heat resistance, improved thermal stability, heat conductivity and minimum wearing of conjugate working parts such as blades. Moreover, the coefficient of linear expansion of such materials must be equal to or approximate that of an alloy from which the turbine rotary shroud rim is fabricated,~
and the turbine sealing members must retain their geometry, should not fall out of the shroud rim and should have a hardness allowing conjugated parts to fit in without appreciable wear in their contact places.
The present invention provides a metal-ceramic nickel-base heat-resistant sealing material whose properties allow its use for manufacturing radial sealing members (parts) operating continuously in gas flows heated to 1000C. 3
The present invention relates -to nickel-base metal-ceramic heat-resistant sealing materials produced by conventional powder metallurgical methods. Such rnaterials prove to be most advantageous when producing sealing memhers (parts) for such units as turbine wheel rims exposed to the effect of gas flows at high temperatures. The nickel-base materials belong to heat-resi~tant metal-ceramic materials which find use in gas turbine pumps and in certain types of surface transport ~ehicles and aircraft.
A nickel-base metal-ceramic heat-resistant material is klown comprising the following alloying elements in per cent by weigh;t: silicon, up to 3, and graphite, up to 8. The material is employed in ~.he manufacture of plates for radial and labyrinth turbine seals.llowever, at a gas flow temperature of about 1000C
these materials are not capable of providing long service life for the machines. This is attributable to the burning-out of their graphite component, through which the surface hardness of the sealing members produced from this material is enhanced with the ensuing higher wear of rotating turbine parts (turbine blades) found in contact therewith.
Moreover, this material is not suitable for producing sealing members (parts) in the form of rolled band, since graphite increases alloy brittleness.
Some nickel-base materials contain from 5 to 20 per cent by weight of silicon, copper, mica, chrom~um or boron r nitride. Such materials are capable of providing long service life of machines but a temperature not in excess of 850C. Thus, the nickel-base materials containing copper can operate, as a , rule, at a temperature not exceeding 600C. Those, comprising mica or micaceous compounds such as vermiculite in muscovite eature lower thermal stability. The materials, compxising chromium (or nichrome-base compounds with the nicke:L-to-chromium - 1- ~ i ~4~26 ratio of 4:1) and boron nitride are inapplicable in machines operating at a temperature above 850~C.
As is commonly known, boron nitride is similar in structure to graphite, bu-t in contras-t to the latter, it has a higher heat resistance and does not burn out in service.
However, the nickel-base materials, containing boron nitride, are prone to cubical oxidation by end products of fuel combustion which causes the geometry of sealing plates to be disturbed and bands in this material to he distorted duriny its usage. At a temperature of gas flows of about 1000C these materials do not provide long-term turbine operation. As the turbine blades wear out, the clearance between the turbine rotary shroud rim and its rotating blades, ~hrough which hot yases can leak, in-creases, this resulting in excessive fuel consumption, lower turbine efficiency and in a decrease in the range of operation of a flying vehicle.
Since the speed of transport vehicles is on the rise, turbine ratings increase as well, with the ensuing rise in the tempera-ture of a gas flow in such turbines. Therefore a need has arisen for providing a nickel-base material which would feature a higher heat resistance, improved thermal stability, heat conductivity and minimum wearing of conjugate working parts such as blades. Moreover, the coefficient of linear expansion of such materials must be equal to or approximate that of an alloy from which the turbine rotary shroud rim is fabricated,~
and the turbine sealing members must retain their geometry, should not fall out of the shroud rim and should have a hardness allowing conjugated parts to fit in without appreciable wear in their contact places.
The present invention provides a metal-ceramic nickel-base heat-resistant sealing material whose properties allow its use for manufacturing radial sealing members (parts) operating continuously in gas flows heated to 1000C. 3
2 -9~2~
The present invention also provides a sealing material which has a small hardness ranging from 25 to 40 kg/mm2 and a higher heat resistance and thermal stability.
The present invention further provides a material suitable for producing insert-pieces for turbine rotary shrouds and allowing turbine blades to fit in without their marked wear.
According to the present invent:ion there is provided a nickel-base metal ceramic heat-resistant sealing material in-cluding boron nitride and silicon dioxide, the weight percentage ` 10 of all the components being:
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
Such material is useful for producing sealing parts and is capable of providing machine, e.g. gas turbine, operation within 3000 hours at a temperature of a gas flow of up to 1000C
or up to 1100C within 500 hours. This is possible because the material comprises the above-specified components in appropriate amounts. As shown experimentally, the introduction of silicon dioxide into the base of the material for instance into powdered nickel makes it possible to enhance heat resistance of the material owing to an increased resistance of nickel against oxidation.
The addition of boron nitride into nickel powder, in the form of a fine powder, enables the hardne~ss of the material E
to ~e decreased owing to separation of nickel grains by boron nitride grains.
The combined introduction of both silicon dioxide and boron nitride in said amounts makes it possible to obtain an oxide .
film at a surface of the material at a working temperature about 1000C. The film adhering firmly to the material, protecting it against further oxidation and very importantly, the thickness of
The present invention also provides a sealing material which has a small hardness ranging from 25 to 40 kg/mm2 and a higher heat resistance and thermal stability.
The present invention further provides a material suitable for producing insert-pieces for turbine rotary shrouds and allowing turbine blades to fit in without their marked wear.
According to the present invent:ion there is provided a nickel-base metal ceramic heat-resistant sealing material in-cluding boron nitride and silicon dioxide, the weight percentage ` 10 of all the components being:
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
Such material is useful for producing sealing parts and is capable of providing machine, e.g. gas turbine, operation within 3000 hours at a temperature of a gas flow of up to 1000C
or up to 1100C within 500 hours. This is possible because the material comprises the above-specified components in appropriate amounts. As shown experimentally, the introduction of silicon dioxide into the base of the material for instance into powdered nickel makes it possible to enhance heat resistance of the material owing to an increased resistance of nickel against oxidation.
The addition of boron nitride into nickel powder, in the form of a fine powder, enables the hardne~ss of the material E
to ~e decreased owing to separation of nickel grains by boron nitride grains.
The combined introduction of both silicon dioxide and boron nitride in said amounts makes it possible to obtain an oxide .
film at a surface of the material at a working temperature about 1000C. The film adhering firmly to the material, protecting it against further oxidation and very importantly, the thickness of
- 3 s '~3 i , ~~he film does not increase in use.
When the silicon dioxide content is less than 0.5 weight per cent, the heat resistance of the mater:Lal decreases and hard- ¦
ness of the working surfaces of the sealing members, produced from this material increases when silicon dioxide is introduced in amounts more than 8 weiyht per cent, the strength of the oxide film deteriorates, it shows a tendency to~ward cracking with the L
film particles being entrained by the gas flow travelling with considerable speeds which may result in a failure of turbine blades.
With a boron nitride content less than 1.0 weight per cent the hardness of the working surfaces of the sealing members increases which causes excessive wear of conjugated parts in ser-vice. When the amount of boron nitride in the material exceeds 10.0 weight per cent, the heat resistance, thermal stability and mechanical strength of such materials deteriorate.
The present invention will be further illustrated by way of the following examples.
Example 1 The following componen-ts are ta~en (weight per cent) for producing a material:
silicon dioxide, 0.5 hexagonal boron nitride, 1.0 nickel, the balance The above-specified components are b~lended in a pow-dered state in a drum mixer. On being charged into a steel die, the mixture is compacted in a hydraulic press to impar-t it the prescribed shape and required strength. The powder compacts then are sintered in electric furnaces in reducing or neutral gases.
The above-outlined procedure is applicable for produc-ing sealing members in the form of plates, rings and bushes. As for the sealing members in the form of band, these can be obtained '~
9L"3;2~
;, ~y rolling bar stock manufactured by compacting and sintering.
The material, according to the invention, from which the abov~-described sealing members were produced comprises, weight per cent: silicon dioxide, 0.5: boron nitride, l.0 and - nickel, the balance.
Said parts are secured either mechanically or by solder-ing them to the rim of a turbine shroud band.
The thus-produced material has the following properties. ¦
An increase in weight upon oxidizing in air at a temperature of 1000C within 100 hours was 0.53 kg/m2, surface hardness amounted to 45 kg/mm2, density - 7.0 g/cm3 and porosity - l9~.
Example 2 A material is produced similarly to that described in Example 1.
The material comprises, weight per cent:
silicon dioxide, 5.0 boron nitride, 5.0 nickel, the balance.
The material has the following properties.
An increase in weigh-t upon oxidizing in air at a temperature of 1000C within 100 hours amounted to 0.70 kg/m2, surface hardness was equal to 4~ kg/mm2, density 6.5 g/cm3 and porosity to 23%
Example 3 A material comprises, weight per cen~:
silicon dioxide, ~.0 ~r boron nitride, 10.0 nickel, the balance.
The material was produced in a similar way to that described in Example 1.
The thus-obtained material has the following proper-ties.
~4~9;~
An increase in weight upon oxidizing in air at a temperature of 1000C within 100 hours amounted to 1.1 kg/m2, sur-face hardness was 45 kg/mm2, density - 6.3 g/cm3 and porosity -25~.
As shown by te~t results, the above-specified material can be advantageously used at elevated temperatures up to 1000C
over several thousand hours. It is also suitable for short-time operation up to 100 hours at a temperature of 1200C.
The material of the present invention has a stable chemical composition, e.g. the chemical composition of a sealing member operated within 2000 hours in a gas flow at a temperature of 1000C did not change and the sealing parts did not exhibit any contraction in spite of continuous vibration.
The sealing material produced according to the present .invention had a higher heat resistance. Upon oxidizing in air at a temperature of 1000C increase in weight amounted to:
during 100 hours 0.38 kg/m2 during 450 hours 0.64 kg/m L
during 1050 hours 0.91 kg/m during 1250 hours 0.95 kg/m2 during 1450 hours 0.95 kg/m2 during 1650 hours 1.04 kg/m2 during 1800 hours l.OS kg/m t during 2000 hours 1.06 kg/m2 during 3000 hours 1.10 kg/m2 The density of the specimens produced from the above material varied from 6.2 to 6.8 g/cm3 and their porosity from 13 to 17%. Initial Brinell hardness amounted to 20-40 kg/mm2. The material features adequate machinability and solderability. Upon testing for thermal stability in a gas burner flame, no cracks were revealed after 300 cycles with each specimen being heated to r 1000C for 60 s and then cooled to 100C within 60 s during .~
-- 6 -- 1~
lE3 ~.~
-z~ .
~ach cycle.
A band, 1-2 mm thick, in the material has an adequate ductility to be bent into a riny at least 30 mm in dia or to be bent and unbent 30 times in one and the same plane.
Coefficient of linear expansion (~ . 106) (20-100) 12.9J1C
~20-700) 15.5/1C
(20-800) 15.9/1C
(20-900) 16.3/1C
(20-1000) 16.4/1C
Coefficient for heat conductivity (cal/cm s C) 25 0.088 100 0.084 F
500 0.078 700 0.078 1000 0.076 . l r f
When the silicon dioxide content is less than 0.5 weight per cent, the heat resistance of the mater:Lal decreases and hard- ¦
ness of the working surfaces of the sealing members, produced from this material increases when silicon dioxide is introduced in amounts more than 8 weiyht per cent, the strength of the oxide film deteriorates, it shows a tendency to~ward cracking with the L
film particles being entrained by the gas flow travelling with considerable speeds which may result in a failure of turbine blades.
With a boron nitride content less than 1.0 weight per cent the hardness of the working surfaces of the sealing members increases which causes excessive wear of conjugated parts in ser-vice. When the amount of boron nitride in the material exceeds 10.0 weight per cent, the heat resistance, thermal stability and mechanical strength of such materials deteriorate.
The present invention will be further illustrated by way of the following examples.
Example 1 The following componen-ts are ta~en (weight per cent) for producing a material:
silicon dioxide, 0.5 hexagonal boron nitride, 1.0 nickel, the balance The above-specified components are b~lended in a pow-dered state in a drum mixer. On being charged into a steel die, the mixture is compacted in a hydraulic press to impar-t it the prescribed shape and required strength. The powder compacts then are sintered in electric furnaces in reducing or neutral gases.
The above-outlined procedure is applicable for produc-ing sealing members in the form of plates, rings and bushes. As for the sealing members in the form of band, these can be obtained '~
9L"3;2~
;, ~y rolling bar stock manufactured by compacting and sintering.
The material, according to the invention, from which the abov~-described sealing members were produced comprises, weight per cent: silicon dioxide, 0.5: boron nitride, l.0 and - nickel, the balance.
Said parts are secured either mechanically or by solder-ing them to the rim of a turbine shroud band.
The thus-produced material has the following properties. ¦
An increase in weight upon oxidizing in air at a temperature of 1000C within 100 hours was 0.53 kg/m2, surface hardness amounted to 45 kg/mm2, density - 7.0 g/cm3 and porosity - l9~.
Example 2 A material is produced similarly to that described in Example 1.
The material comprises, weight per cent:
silicon dioxide, 5.0 boron nitride, 5.0 nickel, the balance.
The material has the following properties.
An increase in weigh-t upon oxidizing in air at a temperature of 1000C within 100 hours amounted to 0.70 kg/m2, surface hardness was equal to 4~ kg/mm2, density 6.5 g/cm3 and porosity to 23%
Example 3 A material comprises, weight per cen~:
silicon dioxide, ~.0 ~r boron nitride, 10.0 nickel, the balance.
The material was produced in a similar way to that described in Example 1.
The thus-obtained material has the following proper-ties.
~4~9;~
An increase in weight upon oxidizing in air at a temperature of 1000C within 100 hours amounted to 1.1 kg/m2, sur-face hardness was 45 kg/mm2, density - 6.3 g/cm3 and porosity -25~.
As shown by te~t results, the above-specified material can be advantageously used at elevated temperatures up to 1000C
over several thousand hours. It is also suitable for short-time operation up to 100 hours at a temperature of 1200C.
The material of the present invention has a stable chemical composition, e.g. the chemical composition of a sealing member operated within 2000 hours in a gas flow at a temperature of 1000C did not change and the sealing parts did not exhibit any contraction in spite of continuous vibration.
The sealing material produced according to the present .invention had a higher heat resistance. Upon oxidizing in air at a temperature of 1000C increase in weight amounted to:
during 100 hours 0.38 kg/m2 during 450 hours 0.64 kg/m L
during 1050 hours 0.91 kg/m during 1250 hours 0.95 kg/m2 during 1450 hours 0.95 kg/m2 during 1650 hours 1.04 kg/m2 during 1800 hours l.OS kg/m t during 2000 hours 1.06 kg/m2 during 3000 hours 1.10 kg/m2 The density of the specimens produced from the above material varied from 6.2 to 6.8 g/cm3 and their porosity from 13 to 17%. Initial Brinell hardness amounted to 20-40 kg/mm2. The material features adequate machinability and solderability. Upon testing for thermal stability in a gas burner flame, no cracks were revealed after 300 cycles with each specimen being heated to r 1000C for 60 s and then cooled to 100C within 60 s during .~
-- 6 -- 1~
lE3 ~.~
-z~ .
~ach cycle.
A band, 1-2 mm thick, in the material has an adequate ductility to be bent into a riny at least 30 mm in dia or to be bent and unbent 30 times in one and the same plane.
Coefficient of linear expansion (~ . 106) (20-100) 12.9J1C
~20-700) 15.5/1C
(20-800) 15.9/1C
(20-900) 16.3/1C
(20-1000) 16.4/1C
Coefficient for heat conductivity (cal/cm s C) 25 0.088 100 0.084 F
500 0.078 700 0.078 1000 0.076 . l r f
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A nickel-base metal-ceramic heat-resistant sealing material, comprising weight per cent:
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
silicon dioxide, from 0.5 to 8.0 boron nitride, from 1.0 to 10.0 nickel, the balance.
2. A material as claimed in claim 1 in which the silicon dioxide and boron nitride are each present in amounts up to 5.0 per cent.
3. A sealing member fabricated of a material as claimed in claim 1 or 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA229,109A CA1044926A (en) | 1975-06-11 | 1975-06-11 | Nickel-base metal-ceramic heat-resistant alloy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA229,109A CA1044926A (en) | 1975-06-11 | 1975-06-11 | Nickel-base metal-ceramic heat-resistant alloy |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044926A true CA1044926A (en) | 1978-12-26 |
Family
ID=4103315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA229,109A Expired CA1044926A (en) | 1975-06-11 | 1975-06-11 | Nickel-base metal-ceramic heat-resistant alloy |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1044926A (en) |
-
1975
- 1975-06-11 CA CA229,109A patent/CA1044926A/en not_active Expired
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