High-Temperature Coatings for Protection Against Turbine Deterioration

1995 ◽  
Vol 117 (1) ◽  
pp. 146-151 ◽  
Author(s):  
W. Tabakoff ◽  
M. Metwally ◽  
A. Hamed
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Erosion Rate ◽  
Wind Erosion ◽  
Protective Coatings ◽  
Impact Angle ◽  
Steam Turbines ◽  
Erosion Behavior

In this research, an investigation was conducted to study the fly ash particles associated with the erosion behavior of alloys and coatings that are widely used in gas and steam turbines. The erosion behavior of many alloys and protective coatings has been investigated experimentally at high temperatures using a specially designed wind erosion tunnel. The erosion results show the effect of velocity, temperature, and impact angle on the erosion rate.

scholarly journals High Temperature Coatings for Protection Against Turbine Deterioration

1993 ◽  
Author(s):  
W. Tabakoff ◽  
M. Metwally ◽  
A. Hamed
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Erosion Rate ◽  
Wind Erosion ◽  
Protective Coatings ◽  
Impact Angle ◽  
Steam Turbines ◽  
Erosion Behavior ◽  
The Impact

In this research, an investigation was conducted to study the fly ash particles associated with the erosion behavior of alloys and coatings which are widely used in gas and steam turbines. The erosion behavior of many alloys and protective coatings has been investigated experimentally at high temperatures using a specially designed wind erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate.

High-Temperature Erosion Resistance of Coatings for Gas Turbine

1992 ◽  
Vol 114 (2) ◽  
pp. 242-249 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed ◽  
M. Metwally ◽  
M. Pasin
Keyword(s):  
High Temperature ◽  
Protective Coatings ◽  
Coal Ash ◽  
Mass Effect ◽  
Impact Angle ◽  
Unit Weight ◽  
Weight Losses ◽  
Aluminide Coatings ◽  
Particle Flows ◽  
The Impact

An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperature. A three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal-ash particles impacting some widely used superalloys and coatings at different angles. The presented results show the variation of the particle restitution ratios with the impingement angle for the coated and uncoated superalloys. The erosion behaviors of INCO-738, MAR 246 and X40 superalloys and protective coatings C, N, RT22 and RT22B also have been investigated experimentally at high temperature using a specially designed erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate (weight loss per unit weight of particles). Based on the experimental results of the particle mass effect on both weight losses and erosion rates, the coating lives have been estimated for different particle concentrations.

Erosion Behavior of Silicon Nitride with Graded Microstructure

2005 ◽  
Vol 287 ◽  
pp. 416-420
Author(s):  
Dae Soon Lim ◽  
Jong In Park ◽  
Dong Phill Lim ◽  
Byung Dong Han ◽  
Dong Soo Park
Keyword(s):  
Weight Loss ◽  
Grain Size ◽  
Thermal Properties ◽  
Silicon Nitride ◽  
High Temperatures ◽  
Depth Profile ◽  
Erosion Rate ◽  
Mechanical And Thermal Properties ◽  
Erosion Behavior ◽  
Auger Depth Profile

Silicon nitride has been considered as candidate tribological material due to their excellent mechanical and thermal properties. This study investigated the effect of graded grain size on the erosion behavior of silicon nitride at room and high temperatures. Erosion tests were carried out with a gas blast-type erosion tester at temperatures up to 800 °C. Weight loss after impact of SiC particles were measured. The erosion rate varied with temperature and microstructure. Different erosion behavior depending on microstructure were discussed based on SEM observation Auger depth profile of worn surfaces.

scholarly journals Numerical Investigation of Wind Erosion to the Grooved Concrete Wall Surface under a Wind-Blown Sand Movement

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Shanqun Chen ◽  
Runchao Tang ◽  
Longzhu Zhang ◽  
Bin Liao
Keyword(s):  
Erosion Rate ◽  
Wind Erosion ◽  
Damage Mechanism ◽  
Impact Angle ◽  
Wall Surface ◽  
Smooth Wall ◽  
Concrete Wall ◽  
Rate Distribution ◽  
Erosion Rates ◽  
Sand Movement

Wind erosion to the grooved concrete wall surface under a wind-blown sand movement was numerically studied. Particularly, the influencing factors that affect the wind erosion to the grooved concrete wall surface were systematically investigated by using the RNG k − ε turbulence model combined with the discrete phase model (DPM). It was found that, under a relatively low impact angle, the damage mechanism to the grooved wall surface is wind-blown sand impact, and the erosion rates of the grooved wall surfaces are higher than those of the smooth wall surfaces. By contrast, under a relatively high impact angle, the damage mechanism to the grooved wall surface transfers to the microcutting effect, and the erosion rates show an opposite trend. The optimization rates between the erosion of grooved and smooth wall surfaces increase with increasing groove size or groove number. However, the damage mechanism to the grooved wall surface is hardly changed by expanding the groove area. The erosion rate distribution and the optimization rates of the groove wall surfaces are not significantly changed by adjusting the spacing between the grooves alone. When the groove shape changes from semicircular to rectangular, the erosion rate distribution is significantly changed, and the wear resistance of the changed grooved wall surface gets better.

scholarly journals Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1833 ◽  
Author(s):  
Dong Lu ◽  
Zhuo Tang ◽  
Liang Zhang ◽  
Jianwei Zhou ◽  
Yue Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Amorphous Phases ◽  
Micro Cracks

Concrete has low porosity and compact microstructure, and thus can be vulnerable to high temperature, and the increasing application of various types of supplementary cementitious materials (SCMs) in concrete makes its high-temperature resistant behavior more complex. In this study, we investigate the effects of four formulations with typical SCMs combinations of fly ash (FA), ultra-fine fly ash (UFFA) and metakaolin (MK), and study the effects of SCMs combinations on the thermal performance, microstructure, and the crystalline and amorphous phases evolution of concrete subjected to high temperatures. The experimental results showed that at 400 °C, with the addition of 20% FA (wt %), the thermal conductivity of the sample slightly increased to 1.5 W/(m·K). Replacing FA with UFFA can further increase the thermal conductivity to 1.7 W/(m·K). Thermal conductivity of concrete slightly increased at 400 °C and significantly reduced at 800 °C. Further, combined usage of SCMs delayed and reduced micro-cracks of concrete subjected to high temperatures. This study demonstrates the potential of combining the usage of SCMs to promote the high-temperature performance of concrete and explains the micro-mechanism of concrete containing SCMs at high temperatures.

scholarly journals Effect of Calcium Carbonate Whisker and Fly Ash on Mechanical Properties of Cement Mortar under High Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Li Wang ◽  
Hongliang Zhang ◽  
Bendong Zhao ◽  
Yang Gao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fly Ash ◽  
Calcium Carbonate ◽  
High Temperatures ◽  
Coupling Effect ◽  
Microstructural Analysis ◽  
Cementitious Materials ◽  
Combined Effect ◽  
Superior Performance

Calcium carbonate (CaCO3) whisker, as a new type of microfibrous material, has been extensively used in the reinforcement of cementitious materials. However, the combined effect of CaCO3 whisker and fly ash on mechanical properties of cementitious materials under high temperatures was still unknown. In this study, the coupling effect of CaCO3 whisker, and fly ash on mechanical properties of the cement was investigated. Two sets of cement mortars were fabricated, including CaCO3 whisker-based mortar which contained 0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.% CaCO3 whisker as cement substitution and CaCO3 whisker-based fly ash mortar which contained 30 wt.% fly ash in addition to 0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.% CaCO3 whisker as cement substitution. Mass loss, compressive strength, and flexural strength of these two sets of specimens before and after being subjected to high temperatures of 200°C, 400°C, 600°C, 800°C, and 1000°C were measured. Based on the results of the aforementioned tests, load-deflection test was performed on the specimen which exhibited the superior performance to further study its mechanical behavior after exposure to high temperatures. Moreover, microstructural analysis, such as mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM), was conducted to reveal the damage mechanism of high temperature and to illustrate the combined effect of CaCO3 whisker and fly ash on high-temperature resistance of the cement. Results showed that fly ash could improve the high-temperature performance of CaCO3 whisker-based mortar before 600°C and limit the loss of strength after 600°C.

scholarly journals Effect of C Content on High Temperature Erosive Wear Characteristics of Fe-Based V Containing Multi-Component Cast Steel with Ni

2018 ◽  
Vol 925 ◽  
pp. 400-407 ◽  
Author(s):  
Kazumichi Shimizu ◽  
Kenta Kusumoto ◽  
Kimitoshi Nakamura ◽  
Shoji Kiguchi ◽  
Masato Shirai ◽  
...  
Keyword(s):  
High Temperature ◽  
Erosion Rate ◽  
Erosion Resistance ◽  
Cast Steel ◽  
Erosive Wear ◽  
Test Machine ◽  
Wear Property ◽  
Erosion Behavior ◽  
High Temperature Erosion ◽  
Hot Hardness

Hot hardness and oxidation property of target material influences greatly on the erosion behavior at elevated temperature. The correlation between hot hardness and oxidation property of multi component white cast irons and its erosion resistance were investigated, and try to estimate the high temperature erosion behavior in the study. Nine kinds of multi component white cast iron and cast steel were used in this study. Specimen were machined into a flat plate with dimension of 50×50×10 mm. High temperature erosion test machine was used to investigate the erosive wear property of experimental materials at 1173K. Alumina grits (average diameter: 1.16 mm, hardness: 1250 HV1) which were used as impact particles were heated to 1073K and shoot on the heated specimen by hot air at the velocity of 100 m/s. The total particle loading was 2 kg. In order to clarify the correlation of hot hardness, oxidation property and the erosion resistance of specimens, hot hardness test was carried out specimens, to estimate erosion damage caused by solid particle. Hot hardness of specimens showed a value comparable to 200～250HV1. Result of erosion and oxidation tests, erosion rate and amount of oxidation of the specimen were suppressed by Ni addition. It suggested that the more amount of Ni contents, the lower the erosion rate and the less the amount of oxidation.

scholarly journals Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4263
Author(s):  
Marta Dudek ◽  
Mateusz Sitarz
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Test Results ◽  
Spectroscopy Analysis ◽  
Granulated Blast Furnace Slag ◽  
Current State ◽  
High Durability ◽  
Digital Microscope ◽  
Microstructure Of The Material

The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

Gamma Titanium Aluminides Behavior at High Temperature Static Short-Term Stress

2014 ◽  
Vol 657 ◽  
pp. 407-411
Author(s):  
Elvira Alexandrescu ◽  
Alexandra Banu ◽  
Mihai Trifănescu ◽  
Alexandru Paraschiv
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Dynamic Testing ◽  
Protective Coatings ◽  
Testing Machine ◽  
High Yield ◽  
Short Term

Today conventional titanium-based alloys represent one third of the weight of modern aircraft engines and, are the second most used engine material following Ni-based superalloys. [1] Titanium aluminide alloys based on intermetallic phases γ (TiAl) and α2 (Ti3Al) and the most recent – orthorhombic titanium aluminide, are widely recognized as having the potential to meet the design requirements for high temperature applications. The outstanding thermo-physical and mechanical properties of these materials rely mainly on the strongly ordered nature and the directional bonding of the compounds. These involve: high melting point, above 1460°C, low density of 3,9-5 g/cm3, according the alloying degree, high elastic modulus (high stiffness), high yield strength and good creep resistance at high temperature, low diffusion coefficient, good structural stability at high temperature. The main objective of our paper are focussed on the short-term mechanical properties if Titanium niobium aluminide at 850°C. High temperatures mechanical properties evaluation was performed by tensile testing at temperature of 850°C on universal static and dynamic testing machine Instron 8802, equipped with high temperature system, for maximum 1000°C, and extensometer with a measuring basis of 40 mm. The mechanical tensile test was performed according the ASTM E8, with control of deformation and a testing rate of 10-4 mmsec.-1. Short-term behavior request of the support uncovered alloys, at 850°C has proved to be modest and it seems obvious that the alloys based on titanium aluminides cannot be used without protective coatings. Key words: titanium aluminides, high temperatures, mechanical properties

scholarly journals Influences of high temperature on mechanical properties of fly ash based geopolymer mortars reinforced with PVA fiber

2021 ◽  
Vol 20 (2) ◽  
pp. 393-406
Author(s):  
Mehmet Kaya ◽  
◽  
Fuat Köksal ◽  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Polyvinyl Alcohol Fiber ◽  
Pva Fiber ◽  
High Temperature Effect

In this study, a geopolymer composite containing PVA fiber was produced to recycle waste fly ash and obtain an eco-friendly binder. Mechanical properties of geopolymer mortars, produced by using F class fly ash which was activated with NaOH (sodium hydroxide), and reinforced by PVA (polyvinyl alcohol) fiber were investigated after high temperature effect. Geopolymer mortar samples produced by mixing with fly ash, sand, water and NaOH were placed in standard molds of 40×40×160 mm3. PVA fibers were used at percentages of 0,5%, 1% and 1,5% by volume in the experiment. Tests were performed on mortars exposed to high temperatures of 200°C, 400°C, 600°C and 800°C for physical and mechanical properties. For the specimens not subjected to high temperatures, an increase in the compressive strength of mortars containing PVA fibers was observed in comparison to mortar without PVA fiber. On the other hand, it was concluded that losses in compressive strength were less for mortar without PVA fiber when compared with the mortars containing PVA fibers. As a result of the modeling, the PVA ratio, which gives the optimum flexural and compressive strength, was determined as 1,47%. As a result of melting of PVA fibers under the effect of high temperature, 83,58% loss of compressive strength was determined in samples containing 1,5% PVA after 800ºC temperature.

Sign in / Sign up

Export Citation Format

Share Document