A Review of Clearance Control Wear Mechanisms for Low Temperature Aluminium Silicon Alloys

1998 ◽  
Author(s):  
F. Ghasripoor ◽  
R.K. Schmid ◽  
M.R. Dorfman ◽  
L. Russo
Keyword(s):  
Wear Mechanisms ◽  
Gas Turbines ◽  
Hexagonal Boron Nitride ◽  
Silicon Alloys ◽  
The Matrix ◽  
Abradable Coatings ◽  
Silicon Based ◽  
Wear Maps ◽  
Clearance Control ◽  
Sprayed Coatings

Abstract Aluminium silicon alloys have shown favourable properties when used as the matrix for abradable coatings in low pressure compressors of gas turbines [1 and 2]. This paper aims to describe the wear mechanisms found in aluminium silicon based abradables. To this end three thermally sprayed coatings are investigated. Aluminium silicon polyester, aluminium silicon-graphite and the most recently developed, aluminium silicon-hexagonal boron nitride (hBN) examined here are amongst a few of these materials. To be able to design materials to functi?n in as wide a parameter range as possible, a test ng simulating engine mechanisms is required. Tests were conducted using titanium blades at velocities ranging from 250 - 450 m/s, temperatures of ambient to 450°C and controlled incursion rate of 5, 50 and 500 µm/s. The data obtained from these tests is best interpreted in the form of wear maps which characterise the seal performance and therefore are of use to engine and material designers.

Wear Mechanisms of Mcraiy Abradable Plasma-Sprayed Coatings

1998 ◽  
Author(s):  
S. Li ◽  
C. Langlade-Bomba ◽  
D. Treheux ◽  
F. Crabos ◽  
P. Monge-Cadet
Keyword(s):  
Wear Mechanisms ◽  
Gas Turbines ◽  
Coating Microstructure ◽  
Blade Tip ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Abradable Coatings ◽  
Engine Components ◽  
New Generation ◽  
Sprayed Coatings

Abstract Reduction of operating clearance between the HP turbine and the shroud in the new generation of gas turbines is one way often used by engine manufacturers to improve efficiency. This implies developing a blade tip coating/shroud coating system to minimize the degradation (particularly blades wear) during eventual rubbing. In this study, the chosen systems are: - VPS NiCoCrAIYTa as HP blade tip coating, - Plasma-sprayed MCrAIY coatings deposited under various atmosphere as abradable coatings. In order to understand the wear mechanisms of these systems tribological tests (block on ring and fretting) were performed to study the influence of the coating microstructure on the wear mechanisms. The results were compared and correlated to those of rub tests performed with real engine components.

scholarly journals Advances in Abradable Coatings for Gas Turbines

1994 ◽  
Author(s):  
R. Schmid ◽  
A. R. Nicoll
Keyword(s):  
Gas Turbines ◽  
Environmental Changes ◽  
Labyrinth Seal ◽  
Operating Conditions ◽  
Mechanism Analysis ◽  
Coating Materials ◽  
Turbine Engine ◽  
Plasma Sprayed ◽  
Abradable Coatings ◽  
Sprayed Coatings

Gas turbine engine development continues to accelerate, creating more demanding requirements for abradable seal coatings. These coatings are necessary to provide very small clearances between the rotating and stationary parts in order to minimize gap losses and so Increase efficiency. The relatively few abradable coating materials developed over the last 20 years still perform well in many blade tip seal and labyrinth seal applications. However, rising operating temperatures, corrosion and other environmental changes, longer overhaul times and even better tip clearances are dictating the design of new coating materials which requires a strong scientific approach. For example, ways are being Investigated to replace Nickel-Graphite and other flame sprayed coatings being used between 450 and 700°C respectively because of steady state/corrosion/oxidation/erosion and wear problems respectively. New plasma and HVOF sprayed coatings have been developed using a systematic approach based on material response to operating conditions, minimizing trial and error. The major steps in the programme were: 1. Selection of constituent materials able to withstand service temperatures up to 325 (AISI-Polyester or Polyimide), 450 (AISI base), 700 (MCrAlY base) and 1100°C (ceramic base) respectively. 2. Powder particle manufacture and coating deposition to guarantee highly reproducible coatings. 3. Coating optimization based on wear tests carried out using a fully instrumented abradability test rig and wear mechanism analysis. 4. An investigation of blade tipping systems for high temperature applications. This paper discusses the results of plasma sprayed coatings developed for use at 450 and 700°C.

Gas turbines use ‘abradable’ coatings for clearance-control seals

2002 ◽  
Vol 2002 (1) ◽  
pp. 7-8 ◽  
Author(s):  
Mitchell Dorfman ◽  
Ulrich Erning ◽  
James Mallon
Keyword(s):  
Gas Turbines ◽  
Abradable Coatings ◽  
Clearance Control

Enhanced thermal conductivity of polyimide composite film filled with hybrid fillers

2021 ◽  
pp. 095400832110003
Author(s):  
Ruiyi Li ◽  
Chengcheng Ding ◽  
Juan Yu ◽  
Xiaodong Wang ◽  
Pei Huang
Keyword(s):  
Thermal Conductivity ◽  
Composite Film ◽  
Hexagonal Boron Nitride ◽  
Composite Films ◽  
Resistance Index ◽  
Reference Value ◽  
Residual Rate ◽  
Practical Applications ◽  
Hybrid Fillers ◽  
The Matrix

In this article, the polyimide (PI) composite films with synergistically improving thermal conductivity were prepared by adding a few graphene nanoplatelets (GNP) and various hexagonal boron nitride (h-BN) contents into the PI matrix. The thermal conductivity of PI composite film with 1 wt% GNP and 30 wt% h-BN content was 1.21 W(m·k)− 1, which was higher than that of the PI composite film with 30 wt% h-BN content (0.45 W(m·k)− 1), the synergistic efficiency of GNP under various h-BN content (10 wt%, 20 wt%, and 30 wt%) were 1.70, 2.71, and 3.09, respectively. And it was found that the increased h-BN content can suppress the dielectric properties caused by GNP in the matrix. The dielectric permittivity and dielectric loss tangent of 1 wt% GNP/PI composite film were 10.69, 0.661 at 103 Hz, respectively, and that of the 30 wt% h-BN + GNP/PI composite film were 4.29 and 0.1367, respectively. Moreover, the mechanical properties of the PI composite film were suitable for practical applications. And the heat resistance index and the residual rate at 700°C of PI composite film increased to 326.8°C, 74.43%, respectively, and these of PI film were 292.6°C and 59.26%. Thus, it may provide a reference value for applying the filler hybridization/PI film in the electronic packaging materials.

Thermally Sprayed Quasicrystal Composite Coatings for Bearings and Other Friction Threaded Applications

2000 ◽  
Author(s):  
E. Lugscheider ◽  
C. Herbst-Dederichs ◽  
A. Reimann
Keyword(s):  
Composite Coatings ◽  
High Hardness ◽  
Atmospheric Plasma ◽  
Ductile Material ◽  
Metallurgical Analysis ◽  
The Matrix ◽  
Material Forming ◽  
Alloy Properties ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Abstract Quasicrystalline phases improve many alloy properties such as thermomechanical stability, thermal and electrical conductivity, and tribological performance. High hardness, however, is accompanied by brittleness, an undesired property in many applications. Reduced brittleness can be achieved by embedding quasicrystalline phases in a more ductile material, forming a metal-matrix composite that retains some quasicrystalline properties. This study evaluates thermally sprayed coatings made from different compositions of such composites. The coatings assessed were produced by arc-wire, HVOF, and atmospheric plasma spraying using various forms of feed material, including blended, agglomerated, chemical encased, and attrition-milled powders and filled wires. The investigation involved metallurgical analysis, proving the existence of quasicrystal content and assessing the matrix phase, and tests showing how sliding wear is influenced by the composition of quasicrystalline phases.

Research of the process of synthesis and properties of the obtained metal-matrix composite powders of the Ti/tib2 system

2021 ◽  
pp. 66-73
Author(s):  
M. E. Goshkoderya ◽  
T. I. Bobkova ◽  
M. V. Staritsyn
Keyword(s):  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Composite Powders ◽  
Optimal Ratio ◽  
The Matrix ◽  
Series Of Experiments ◽  
Sprayed Coatings

The paper proposes a method for preparing composite powders of the Ti/TiB2 system, studies the properties of the obtained composite powders, and also shows a series of experiments on its microplasma spraying. The properties of the sprayed coatings were investigated. On its basis the optimal ratio of the matrix and reinforcing components was established in order to increase significantly the hardness of the sprayed coatings.

Tool Wear Mechanisms during Machining of Alloy 625

2011 ◽  
Vol 275 ◽  
pp. 204-207 ◽  
Author(s):  
Lenka Fusova ◽  
Pawel Rokicki ◽  
Zdeněk Spotz ◽  
Karel Saksl ◽  
Carsten Siemers
Keyword(s):  
Wear Mechanisms ◽  
Gas Turbines ◽  
Metal Cutting ◽  
Elevated Temperatures ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Production Costs ◽  
Chemical Compositions ◽  
Alloy 625 ◽  
Wide Range

Nickel-base superalloys like Alloy 625 are widely used in power generation applications due to their unique properties especially at elevated temperatures. During the related component manufacturing for gas turbines up to 50% of the material has to be removed by metal cutting operations like milling, turning or drilling. As a result of high strength and toughness the machinability of Alloy 625 is generally poor and only low cutting speeds can be used. High-speed cutting of Alloy 625 on the other hand gets more important in industry to reduce manufacturing times and thus production costs. The cutting speed represents one of the most important factors that have influences on the tool life. The aim of this study is the analyses of wear mechanisms occurring during machining of Alloy 625. Orthogonal cutting experiments have been performed and different process parameters have been varied in a wide range. New and worn tools have been investigated by stereo microscopy, optical microscopy and scanning electron microscopy. Energy-dispersive X-ray analyses were used for the investigation of chemical compositions of the tool's surface as well as the nature of reaction products formed during the cutting process. Wear mechanisms observed in the machining experiments included abrasion, fracture and tribochemical effects. Specific wear features appeared depending on the mechanical and thermal conditions generated in the wear zones.

Tribological and Corrosion Behavior of HVOF Sprayed Cr3C2-NiCr with Nickel Cladded Graphite and Hexagonal Boron Nitride

2021 ◽  
Author(s):  
M. Oechsner ◽  
T. Engler ◽  
H. Scheerer ◽  
Y. Joung ◽  
K. Bobzin ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Friction And Wear ◽  
Room Temperature ◽  
Solid Lubricant ◽  
Hexagonal Boron Nitride ◽  
Solid Lubricants ◽  
Wear Behaviour ◽  
Wear Volume ◽  
Coating Microstructure ◽  
Sprayed Coatings

Abstract High-velocity oxyfuel (HVOF) sprayed coatings of Cr3C2-NiCr containing solid lubricants such as nickel cladded graphite and hexagonal boron nitride were successfully developed and characterised with the aim of optimizing their friction and wear behaviour. HVOF technology was used for the integration of solid lubricants to achieve strong cohesion between particles while minimizing thermal decomposition. Coating microstructure and composition were measured and correlated to the results of tribological and corrosion tests. The integration of the solid lubricant greatly reduced friction and wear volume at room temperature, but the lubricating effect was highly dependent on atmosphere and temperature. Cr3C2-NiCr with hBN, however, tends to exhibit more stable wear resistance over a wider temperature range and can be used at temperatures beyond 450 °C.

Comparative analysis of tribological behavior of plasma- and high-velocity oxygen fuel-sprayed WC-10Co-4Cr coatings

2017 ◽  
Vol 69 (2) ◽  
pp. 325-332 ◽  
Author(s):  
Shiyu Cui ◽  
Qiang Miao ◽  
Wenping Liang ◽  
Yi Xu ◽  
Baiqiang Li
Keyword(s):  
Plasma Spraying ◽  
High Velocity ◽  
Wear Mechanisms ◽  
Wear Behavior ◽  
High Velocity Oxygen Fuel ◽  
Hvof Spraying ◽  
Content Type ◽  
Q235 Steel ◽  
Oxygen Fuel ◽  
Sprayed Coatings

Purpose The purpose of this study is to prepare WC-10Co-4Cr coatings using two processes of plasma spraying and high-velocity oxygen fuel (HVOF) spraying. The decarburization behaviors of the different processes are analyzed individually. The microstructural characteristics of the as-sprayed coatings are presented and the wear mechanisms of the different WC–10Co–4Cr coatings are discussed in detail. Design/methodology/approach The WC–10Co–4Cr coatings were formed on the surface of Q235 steel by plasma and HVOF spraying. Findings Plasma spraying causes more decarburizing decomposition of the WC phase than HVOF spraying. In the plasma spraying process, η(Cr25Co25W8C2) phase appears and the C content decreases from the top surface of the coating to the substrate. Practical implications In this study, two WC–10Co–4Cr coatings on Q235 steel prepared by plasma and HVOF spraying were compared with respect to the sliding wear behavior. Originality/value The wear mechanisms of the plasma- and HVOF-sprayed coatings were abrasive and oxidation, respectively.

Low-Leakage Modular Regenerators for Gas-Turbine Engines

1997 ◽  
Author(s):  
James Anthony Kluka ◽  
David Gordon Wilson
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Regenerative Heat ◽  
Turbine Engine ◽  
Low Leakage ◽  
The Matrix ◽  
Potential Applications ◽  
Ceramic Honeycomb

One of the significant problems plaguing regenerator designs is seal leakage resulting in a reduction of thermal efficiency. This paper describes the preliminary design and analysis of a new regenerative heat-exchanger concept, called a modular regenerator, that promises to provide improved seal-leakage performance. The modular regenerator concept consists of a ceramic-honeycomb matrix discretized into rectangular blocks, called modules. Separating the matrix into modules substantially reduces the transverse sealing lengths and substantially increases the longitudinal sealing lengths as compared with typical rotary designs. Potential applications can range from small gas-turbine engines for automotive applications to large stationary gas turbines for industrial power generation. Descriptions of two types of modular regenerators are presented including sealing concepts. Results of seal leakage analysis for typical modular regenerators sized for a small gas-turbine engine (120 kW) predict leakage rates under one percent for most seal-clearance heights.

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