scholarly journals Micro-Structures and High-Temperature Friction-Wear Performances of Laser Cladded Cr–Ni Coatings

Materials ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 137 ◽  
Author(s):  
Li Jiahong ◽  
Kong Dejun
Keyword(s):  
High Temperature ◽  
Micro Structures

scholarly journals Experimental study on high temperature mechanical properties of aluminate cement mortar mixed with fiber

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4441-4448
Author(s):  
Ping Xu ◽  
Dong Han ◽  
Jian-Xin Yu ◽  
Yu-Hao Cui ◽  
Min-Xia Zhang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Cement Mortar ◽  
Steel Fibers ◽  
Basalt Fibers ◽  
High Temperature Mechanical Properties ◽  
Micro Structures ◽  
Aluminate Cement

The aim of the present paper is to study the mechanical properties of aluminate cement mortar mixed with different chopped fibers under high temperature. The specimens with a size of 40 mm ? 40 mm ? 160 mm is treated at various tempera?tures of 25?C, 200?C, 400?C, 600?C, and 800?C. The compressive and flexural strength of the aluminate cement mortar and its micro-structures are tested. The results show that the chopped steel fibers and basalt fibers are effective in improv?ing the high temperature mechanical properties of aluminate cement mortar. When the volume fraction of chopped steel fibers is 2%, the compressive strength and flexural strength of the test block treated at the temperature of 800?C increase by 18.3% and 128.6%, respectively.

Shark-skin inspired surface engineering on intermetallic titanium aluminides for high temperature applications using the fluorine effect

2011 ◽  
Vol 1295 ◽  
Author(s):  
Raluca Pflumm ◽  
Michael Schütze
Keyword(s):  
High Temperature ◽  
Surface Engineering ◽  
Titanium Aluminides ◽  
Single Digit ◽  
New Developments ◽  
Shark Skin ◽  
The Stability ◽  
Micro Structures ◽  
Temperature Applications

ABSTRACTIncreasing demands on technical components for high-temperature applications (e.g. tur-bine blades) promote new developments not only in the field of alloy design, but also in surface engineering. This paper shows that it is possible to structure the surface of intermetallic titanium aluminides in-situ by locally controlled oxidation of the material due to selective doping with fluorine. The aim is to reproduce a shark-skin pattern (parallel riblets with valleys in between) in order to improve the surface aerodynamics. Riblets with widths in the single digit μm range have been generated. The nucleation process, the aspect ratio and the stability of the generated micro-structures are discussed as a function of the substrate composition and the oxidation conditions.

Thermal Fatigue Reliability of High-Temperature-Resistant Joint for Power Devices

2009 ◽  
Author(s):  
Hiromi Sugihara ◽  
Masanori Yamagiwa ◽  
Masato Fujita ◽  
Toshikazu Oshidari ◽  
Qiang Yu
Keyword(s):  
High Temperature ◽  
Thermal Fatigue ◽  
Critical Issue ◽  
Nano Particles ◽  
Fatigue Reliability ◽  
Analysis Model ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Higher Temperature ◽  
Micro Structures

The power electronics equipments for Electric vehicles such as the inverter are strongly demanded on downsizing and weight reduction. For these requirements, Silicon Carbide (SiC) devices are receiving particular attention. SiC devices are characterized by lower-loss and higher temperature operation compared with Si devices. Using the devices under high temperature, the cooling equipments can be miniaturized. However, a function of stress relaxation that the existing solder has is difficult to be expected in a high-temperature-resistant joint layer for SiC devices, because the joint layer is generally hard. So, the authors have proposed a new mounting structure that a metal circuit on a substrate has the function instead of the joint layer. In this study, high-temperature-resistant mounting structures that the chip was bonded by low temperature sintering method using Ag nano-particles to substrate with Ag/Ni plating are prepared. Thermal Cycle Test (TCT) using these samples of harsh temperature range was conducted. As a result a new critical issue on the chip joint was identified. To clarify the thermal fatigue mechanism, the Finite-Element-Analysis (FEA) was carried out. The analysis model simulated a thin layer of Ag/Ni plating and the high-temperature-resistant joint layer. By the FEM results, the thermal fatigue, particularly occurring crack, was affected by the micro structures.

Numerical Simulation of High Temperature Deformation Behavior of Nickel-Based Superalloys Using Crystal Plasticity Models and Finite Element Method

2017 ◽  
pp. 414-446
Author(s):  
M. K. Samal
Keyword(s):  
High Temperature ◽  
Crystal Plasticity ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Micro Structure ◽  
Gamma Prime ◽  
Multi Scale ◽  
Crystal Plasticity Model ◽  
Micro Structures

Development of reliable computational models to predict the high temperature deformation behavior of nickel based super-alloys is in the forefront of materials research. These alloys find wide applications in manufacturing of turbine blades and discs of aircraft engines. The micro-structure of these alloys consists of the primary gamma-prime phase and the secondary and tertiary precipitates (of Ni3Al type) are dispersed as gamma-prime phases in the gamma-matrix. It is computationally expensive to incorporate the explicit finite element model of the micro-structure in a crystal plasticity based constitutive framework to simulate the response of the polycrystalline micro-structure. Existing models in literature do not account for these underlying micro-structural features which are important for simulation of polycrystalline response. The aim of this chapter is to present a physically-motivated multi-scale approach for simulation of high temperature response of Nickel-based super-alloys. At the lower length scale, a dislocation density based crystal plasticity model is developed which simulates the response of various types of micro-structures. The micro-structures are designed with various shapes and volume fractions of gamma-prime precipitates. A new model for simulation of the mechanism of anti-phase boundary shearing of the gamma-prime precipitates, by the matrix dislocations, is presented in this chapter. The lower scale model is homogenized as a function of various micro-structural parameters and the homogenized model is used in the next scale of multi-scale simulation. In addition, a new criterion for initiation of micro-twin and a constitutive model for twin strain accumulation are developed. This new micro-twin model along with the homogenized crystal plasticity model has been used to simulate the creep response of a single crystal nickel-based super-alloy and the results have been compared with those of experiment from literature. It was observed that the new model has been able to model the tension-compression asymmetry as observed in single crystal experiments.

Numerical Simulation of High Temperature Deformation Behavior of Nickel-Based Superalloys Using Crystal Plasticity Models and Finite Element Method

2017 ◽  
pp. 341-373
Author(s):  
M. K. Samal
Keyword(s):  
High Temperature ◽  
Crystal Plasticity ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Micro Structure ◽  
Gamma Prime ◽  
Multi Scale ◽  
Crystal Plasticity Model ◽  
Micro Structures

Development of reliable computational models to predict the high temperature deformation behavior of nickel based super-alloys is in the forefront of materials research. These alloys find wide applications in manufacturing of turbine blades and discs of aircraft engines. The micro-structure of these alloys consists of the primary gamma-prime phase and the secondary and tertiary precipitates (of Ni3Al type) are dispersed as gamma-prime phases in the gamma-matrix. It is computationally expensive to incorporate the explicit finite element model of the micro-structure in a crystal plasticity based constitutive framework to simulate the response of the polycrystalline micro-structure. Existing models in literature do not account for these underlying micro-structural features which are important for simulation of polycrystalline response. The aim of this chapter is to present a physically-motivated multi-scale approach for simulation of high temperature response of Nickel-based super-alloys. At the lower length scale, a dislocation density based crystal plasticity model is developed which simulates the response of various types of micro-structures. The micro-structures are designed with various shapes and volume fractions of gamma-prime precipitates. A new model for simulation of the mechanism of anti-phase boundary shearing of the gamma-prime precipitates, by the matrix dislocations, is presented in this chapter. The lower scale model is homogenized as a function of various micro-structural parameters and the homogenized model is used in the next scale of multi-scale simulation. In addition, a new criterion for initiation of micro-twin and a constitutive model for twin strain accumulation are developed. This new micro-twin model along with the homogenized crystal plasticity model has been used to simulate the creep response of a single crystal nickel-based super-alloy and the results have been compared with those of experiment from literature. It was observed that the new model has been able to model the tension-compression asymmetry as observed in single crystal experiments.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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