Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running cl...Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running clearances between the rotating and stationary components.The main benefit of reduction in the clearances is efficiency gains,resulting in lowered fuel consumption and polluting gas emissions,with ecological and economic advantages.However,at these undersized clearances,some rubbing interactions are unavoidable,which can be accommodated by applying Abradable Sealing Coatings(ASCs)on the stationary inner surface.This paper reviews the commercially available abradable materials for thermal spraying at various application positions and temperatures.Emphasis is placed on the abradability and wear mechanisms involved.In addition,considering the tendency of SiC/SiC ceramic matrix composites replacing superalloys as hot section components,the future prospect of ceramic abradables based on Environmental Barrier Coatings(EBCs)in turbine stages is summarized and a new concept of"self-degradable ceramics"based on the corrosive steam environment is proposed for the purpose of high-temperature fillerfree abradables.展开更多
In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the cor...In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the corrosion failure.Through the composition and structure analysis,the corrosion process of the system was predicted and then verified with mercury intrusion porosimetry,cross-section SEM/EDS analysis,and electrochemical measurements.The results demonstrated that the interphase selective corrosion caused the porosity of the top layer to decrease first and then increase during the corrosion development.The interlayer galvanic corrosion,determined by the pore connectivity,is crucial for corrosion failure.展开更多
As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research pr...As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research progress in InFeO3（ZnO）m that were developed in our group. We first introduced a series of conventional abradable seal coating materials as a research motivation. Second, the phase composition and crystal structures of lnFeO3（ZnO）m system were presented. Then, their thermophysical properties, as the most important part, were introduced in detail. At last, the mechanical properties such as hardness, friction coefficient, erosion wear resistance of InFeO3（ZnO）m system were also described. Our summary indicates that InFeO3（ZnO）m sys- tems are promising abradable seal coating materials.展开更多
Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block.Bond coating was prepared by atm...Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block.Bond coating was prepared by atmospheric plasma spraying and top coating was prepared by flame spraying.The microstructure,mechanical properties and abradability of the coating were characterized by scanning elec-tron microscope(SEM),hardness tester,universal testing machine,thermal shock testing machine and abradability testing machine.The res-ults show that the overall spraying structure of the seal coating is uniform,the nickel metal phase is the skeleton supporting the entire coat-ing,and the coating is well bonded without separation.The seal coating has a bonding strength of not less than 7.7 MPa,excellent thermal stability,and thermal shock resistance cycle numbers at 500℃more than 50;the scratch length,deepest invasion depth and wear amount of the coating increase with rise of test temperature,with almost no coating adhesion,indicating that the seal coating has excellent abradability.展开更多
Abradable seal rubber has been widely used in aero-engine fans to improve their efficiency by reducing the clearance between rotating and stationary components. To investigate the high-speed scraping behavior between ...Abradable seal rubber has been widely used in aero-engine fans to improve their efficiency by reducing the clearance between rotating and stationary components. To investigate the high-speed scraping behavior between a vulcanized silicone rubber and a Ti-6Al-4V fan blade and evaluate the abradable performance of seal rubber, abrasion tests were conducted at a blade tip velocity of 50–300 m/s with an incursion rate of 100 lm/s. The influences of the blade tip velocity on the wear mechanism and interaction forces were specially analyzed. It is shown that abrasive wear and pattern wear are the predominant wear mechanisms, and pattern wear can be seen as the emergence and propagation of cracks. With an increase of the blade tip velocity, both of the final incursion depth and wear mass loss of seal rubber exhibit growth trends. The gradual changes of rubbing forces with an increase of rubbing time are the characteristic of abrasive wear, and force curves with unstable mutations are a reflection of pattern wear. At a constant incursion rate of 100 lm/s, the maximum values of interaction forces decrease first and then grow with an increase of the blade tip velocity, and the blade tip velocity of 150 m/s becomes the cut-off point between abrasive wear and pattern wear.展开更多
Traditional processes for machining mold cavities are lengthy and costly. EDM (electro-discharge machining) is the most commonly used technique to obtain complex mold cavities. However, some electrodes are difficult t...Traditional processes for machining mold cavities are lengthy and costly. EDM (electro-discharge machining) is the most commonly used technique to obtain complex mold cavities. However, some electrodes are difficult to fabricate because of the complexity. Applying RP (rapid prototyping) technology to fabricate an abrading tool which is used to abrade graphite EDM electrodes, the cost and cycle time can greatly be reduced. The paper describes the work being conducted in this area by the authors. This technique will find widespread application in rapid steel mold manufacturing.展开更多
The paper deals with the properties of wetlaid nonwovens and their composites in two different blended fibers (polyester and aromatic fiber pulp) and ceramic fiber pulp mainly. The conclusion is that high blending rat...The paper deals with the properties of wetlaid nonwovens and their composites in two different blended fibers (polyester and aromatic fiber pulp) and ceramic fiber pulp mainly. The conclusion is that high blending ratio of blended fiber will lead to the worse properties of the products.展开更多
In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, ...In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, a Ni/cBN abrasive coating was prepared on titanium alloy using electrodeposition. The high-speed rubbing tests with a linear velocity of 350 m/s and different incursion rates were performed to investigate the effect of the Ni/cBN abrasive coating on the wear behavior against NiCrAl/diatomite seal coating. Results showed that melting wear and adhesive transfer occurred on the bare blades, causing the bare blade to suffer excessive wear. While the Ni/cBN abrasive coating exhibited superior wear resistance and cutting performance. The cBN grits pullout, the abrasion of Ni matrix and transfer of seal coating to the cBN grits were the main wear mechanism of the Ni/cBN abrasive coating. Additionally, it was found that the relationship between the incursion rate and high-speed rubbing behavior is quite different for the bare blade and Ni/cBN coating. The reason for the difference in wear behavior of bare blade and Ni/cBN coating at different incursion rates was discussed in detail.展开更多
The paper is to outline a new process for manufacturing rapid graphite electrode. It detailsthe steps in Providing integration with Rapid Prototyping (RP) into rapid electrode abrading Process.The key to this combinat...The paper is to outline a new process for manufacturing rapid graphite electrode. It detailsthe steps in Providing integration with Rapid Prototyping (RP) into rapid electrode abrading Process.The key to this combination is the successful model or patted creating using the RP technology.Significantly reduced lead-time, shortened learns curve, lowered revision changes cost and eliminatedor reduced mold polishing are the consequent results. high quality Electrical Discharge Machining(EDM) electrodes are sometimes difficult to be manufactured rapidly and are very time-consumingby conventional methods, even using Computer Numerical Control (CNC) machines. Abradingprovides a simple way to create etuemely detailed and complex electrode to make molds in toolingmaking industries. Integration with the rapid development of the Rapid Prototyping & Manufacturing(RP&M) technology, the rapid electrode abrading process has been regarded as one of the majorbreakthrough in tooling making technology.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.U2241238,52275461,and 92060201)the Major Program(JD)of Hubei Province,China(No.2023BAA003)the Key Research and Development Program of Hubei Province,China(No.2023BAB107).
文摘Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running clearances between the rotating and stationary components.The main benefit of reduction in the clearances is efficiency gains,resulting in lowered fuel consumption and polluting gas emissions,with ecological and economic advantages.However,at these undersized clearances,some rubbing interactions are unavoidable,which can be accommodated by applying Abradable Sealing Coatings(ASCs)on the stationary inner surface.This paper reviews the commercially available abradable materials for thermal spraying at various application positions and temperatures.Emphasis is placed on the abradability and wear mechanisms involved.In addition,considering the tendency of SiC/SiC ceramic matrix composites replacing superalloys as hot section components,the future prospect of ceramic abradables based on Environmental Barrier Coatings(EBCs)in turbine stages is summarized and a new concept of"self-degradable ceramics"based on the corrosive steam environment is proposed for the purpose of high-temperature fillerfree abradables.
基金financially supported by the National Natural Science Foundation of China(No.51671198)。
文摘In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the corrosion failure.Through the composition and structure analysis,the corrosion process of the system was predicted and then verified with mercury intrusion porosimetry,cross-section SEM/EDS analysis,and electrochemical measurements.The results demonstrated that the interphase selective corrosion caused the porosity of the top layer to decrease first and then increase during the corrosion development.The interlayer galvanic corrosion,determined by the pore connectivity,is crucial for corrosion failure.
基金financially supported by the National Natural Science Foundation of China(Nos.51671015,51571007 and 51772012)the Beijing Municipal Science and Technology Commission(No.Z171100002017002)the Shenzhen Peacock Plan team(No.KQTD2016022619565911)
文摘As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research progress in InFeO3（ZnO）m that were developed in our group. We first introduced a series of conventional abradable seal coating materials as a research motivation. Second, the phase composition and crystal structures of lnFeO3（ZnO）m system were presented. Then, their thermophysical properties, as the most important part, were introduced in detail. At last, the mechanical properties such as hardness, friction coefficient, erosion wear resistance of InFeO3（ZnO）m system were also described. Our summary indicates that InFeO3（ZnO）m sys- tems are promising abradable seal coating materials.
基金supported by Zhejiang Provincial Science and Technology Plan Project(Grant No.2022C01118).
文摘Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block.Bond coating was prepared by atmospheric plasma spraying and top coating was prepared by flame spraying.The microstructure,mechanical properties and abradability of the coating were characterized by scanning elec-tron microscope(SEM),hardness tester,universal testing machine,thermal shock testing machine and abradability testing machine.The res-ults show that the overall spraying structure of the seal coating is uniform,the nickel metal phase is the skeleton supporting the entire coat-ing,and the coating is well bonded without separation.The seal coating has a bonding strength of not less than 7.7 MPa,excellent thermal stability,and thermal shock resistance cycle numbers at 500℃more than 50;the scratch length,deepest invasion depth and wear amount of the coating increase with rise of test temperature,with almost no coating adhesion,indicating that the seal coating has excellent abradability.
基金supported by the Fundamental Research Funds for the Central Universities (No. 2013XZZX005)
文摘Abradable seal rubber has been widely used in aero-engine fans to improve their efficiency by reducing the clearance between rotating and stationary components. To investigate the high-speed scraping behavior between a vulcanized silicone rubber and a Ti-6Al-4V fan blade and evaluate the abradable performance of seal rubber, abrasion tests were conducted at a blade tip velocity of 50–300 m/s with an incursion rate of 100 lm/s. The influences of the blade tip velocity on the wear mechanism and interaction forces were specially analyzed. It is shown that abrasive wear and pattern wear are the predominant wear mechanisms, and pattern wear can be seen as the emergence and propagation of cracks. With an increase of the blade tip velocity, both of the final incursion depth and wear mass loss of seal rubber exhibit growth trends. The gradual changes of rubbing forces with an increase of rubbing time are the characteristic of abrasive wear, and force curves with unstable mutations are a reflection of pattern wear. At a constant incursion rate of 100 lm/s, the maximum values of interaction forces decrease first and then grow with an increase of the blade tip velocity, and the blade tip velocity of 150 m/s becomes the cut-off point between abrasive wear and pattern wear.
基金The work in this paper is supported by NSFC fund under the contract No.59775066.
文摘Traditional processes for machining mold cavities are lengthy and costly. EDM (electro-discharge machining) is the most commonly used technique to obtain complex mold cavities. However, some electrodes are difficult to fabricate because of the complexity. Applying RP (rapid prototyping) technology to fabricate an abrading tool which is used to abrade graphite EDM electrodes, the cost and cycle time can greatly be reduced. The paper describes the work being conducted in this area by the authors. This technique will find widespread application in rapid steel mold manufacturing.
文摘The paper deals with the properties of wetlaid nonwovens and their composites in two different blended fibers (polyester and aromatic fiber pulp) and ceramic fiber pulp mainly. The conclusion is that high blending ratio of blended fiber will lead to the worse properties of the products.
基金supported by the National Science and Technology Major Project(2017-VII-0012-0108).
文摘In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, a Ni/cBN abrasive coating was prepared on titanium alloy using electrodeposition. The high-speed rubbing tests with a linear velocity of 350 m/s and different incursion rates were performed to investigate the effect of the Ni/cBN abrasive coating on the wear behavior against NiCrAl/diatomite seal coating. Results showed that melting wear and adhesive transfer occurred on the bare blades, causing the bare blade to suffer excessive wear. While the Ni/cBN abrasive coating exhibited superior wear resistance and cutting performance. The cBN grits pullout, the abrasion of Ni matrix and transfer of seal coating to the cBN grits were the main wear mechanism of the Ni/cBN abrasive coating. Additionally, it was found that the relationship between the incursion rate and high-speed rubbing behavior is quite different for the bare blade and Ni/cBN coating. The reason for the difference in wear behavior of bare blade and Ni/cBN coating at different incursion rates was discussed in detail.
文摘The paper is to outline a new process for manufacturing rapid graphite electrode. It detailsthe steps in Providing integration with Rapid Prototyping (RP) into rapid electrode abrading Process.The key to this combination is the successful model or patted creating using the RP technology.Significantly reduced lead-time, shortened learns curve, lowered revision changes cost and eliminatedor reduced mold polishing are the consequent results. high quality Electrical Discharge Machining(EDM) electrodes are sometimes difficult to be manufactured rapidly and are very time-consumingby conventional methods, even using Computer Numerical Control (CNC) machines. Abradingprovides a simple way to create etuemely detailed and complex electrode to make molds in toolingmaking industries. Integration with the rapid development of the Rapid Prototyping & Manufacturing(RP&M) technology, the rapid electrode abrading process has been regarded as one of the majorbreakthrough in tooling making technology.
