Investigation on Friction and Thermal Expansion Coefficients of Al-Sn Bearing Alloys

2007 ◽  
Vol 353-358 ◽  
pp. 3063-3066 ◽  
Author(s):  
Yong Zhi Zou ◽  
Zheng Bin Xu ◽  
Yan Gao ◽  
Hong Gu ◽  
Jian Min Zeng
Keyword(s):  
Thermal Expansion ◽  
Friction Coefficient ◽  
Testing Machine ◽  
Alloy System ◽  
The Other ◽  
Thermal Expansion Coefficients ◽  
Friction Testing ◽  
Other Hand ◽  
Expansion Coefficients

The influences of Sn addition of 3%-30% on the friction and thermal expansion properties of Al-Sn bearing alloys were investigated in this paper. The experiments were carried out on a specially designed friction testing machine and a dilatometer. It is shown by the experiments that the friction coefficient and hardness of the alloys decrease with the increasing of Sn content. The friction coefficient decreases dramatically when Sn content is higher than 6%. On the other hand, the friction coefficient is also dependent on the load. The friction coefficient increases as the load rises. The linear CTE is also a function of temperature and Sn contents. CTE increases when the temperature rises but has no obvious differences for the alloy system when the temperature is below 80°C. As the temperature rises, the differences become large among the alloy system. The higher the Sn content, the lower the CTE.

The Influence of γ/γ′ Morphology on the Rafting and Stress Distribution of Nickel-Based Superalloys Loaded in [0 0 1] Direction

2017 ◽  
Vol 895 ◽  
pp. 14-19
Author(s):  
Xin Mei Wang ◽  
M.Y. Cao ◽  
S.W. Li ◽  
Z.Y. Yu ◽  
Z.F. Yue
Keyword(s):  
Thermal Expansion ◽  
Stress Distribution ◽  
Tensile Loading ◽  
The Other ◽  
Misfit Stress ◽  
Thermal Expansion Coefficients ◽  
User Subroutine ◽  
Expansion Coefficients ◽  
Two Phases ◽  
Oriented Single Crystal

Two kinds of representative volume elements (RVEs) are introduced to represent the experimental γ/γ′ morphology to study the influences of microstructures on the creep behavior of [0 0 1]-oriented single crystal nickel-based superalloys under tensile loading. One RVE (RVE1) is consisted with one cuboidal γ′ phase surrounded by γ phase. The other (RVE2) is constructed by two cuboidal γ′ phases and one rectangle γ′ phase. A raft criterion is implemented into a user subroutine to predict the rafting type. The misfit stress is considered by different thermal expansion coefficients of the two phases. The rafting type is correctly predicted. The evolutions of the stresses distributions are discussed.

Influence of Aggregates on Cracking Resistance of Concrete at Early Age

2012 ◽  
Vol 151 ◽  
pp. 474-479
Author(s):  
Bo Chen ◽  
Jian Tong Ding ◽  
Yue Bo Cai
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Stress Testing ◽  
Testing Machine ◽  
Tensile Creep ◽  
Early Age ◽  
Test Results ◽  
Cracking Resistance ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

In order to investigate influence of aggregates on cracking resistance of concrete at early age, four kinds of aggregates, i.e. syenite, basalt, marble and sandstone, were used for the test on cracking resistance of hydraulic concretes by the temperature stress testing machine. Analogy analysis was carried out with test results of concretes with two gradings of aggregates. The results show that aggregates affect elastic modulus, thermal expansion coefficients and tensile creep behavior of concrete at early age. However, the temperature rise of concrete was slightly affected by various types and gradings of aggregate. Moreover, the cracking temperature is reliably to be used to quantitatively evaluate the influence of aggregates on cracking resistance of concrete at early age.

Influence of Cr deficiency on sintering, thermal expansion and electrical properties of La0.75Sr0.25Cr1−xO3−δ as a SOFC interconnect material

2016 ◽  
Vol 30 (11) ◽  
pp. 1650127 ◽  
Author(s):  
Yi Ren ◽  
Wen Ma ◽  
Xiaoying Li ◽  
Jun Wang ◽  
Yu Bai ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Electrical Properties ◽  
Perovskite Phase ◽  
Ignition Process ◽  
Thermal Expansion Coefficients ◽  
Auto Ignition ◽  
Pure Perovskite Phase ◽  
Maximum Conductivity ◽  
Expansion Coefficients ◽  
Interconnect Material

The SOFC interconnect materials La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] [Formula: see text]–[Formula: see text] were prepared using an auto-ignition process. The influences of Cr deficiency on their sintering, thermal expansion and electrical properties were investigated. All the samples were pure perovskite phase after sintering at 1400[Formula: see text]C for 4 h. The cell volume of La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] decreased with increasing Cr deficient content. The relative density of the sintered bulk samples increased from 93.2% [Formula: see text] to a maximum value of 94.7% [Formula: see text] and then decreased to 87.7% [Formula: see text]. The thermal expansion coefficients of the sintered bulk samples were in the range of [Formula: see text]–[Formula: see text] (30–1000[Formula: see text]C), which are compatible with that of YSZ. Among the investigated samples, the sample with 0.02 Cr deficiency had a maximum conductivity of 40.4 Scm[Formula: see text] and the lowest Seebeck coefficient of 154.8 [Formula: see text]VK[Formula: see text] at 850[Formula: see text]C in pure He. The experimental results indicate that La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] has the best properties and is much suitable for SOFC interconnect material application.

Novel Silicon-Elastomers for Advanced Soft Lithography

2006 ◽  
Vol 947 ◽  
Author(s):  
Kyung Choi
Keyword(s):  
Thermal Expansion ◽  
High Resolution ◽  
Soft Lithography ◽  
Materials Properties ◽  
Nano Scale ◽  
Thermal Expansion Coefficients ◽  
High Thermal Expansion ◽  
Expansion Coefficients

ABSTRACTHigh resolution pattern transfers in the nano-scale regime have been considerable challenges in ‘soft lithography’ to achieve nanodevices with enhanced performances. In this technology, the resolution of pattern integrations is significantly rely on the materials' properties of polydimethylsiloxane (PDMS) stamps. Since commercial PDMS stamps have shown limitations in nano-scale resolution soft lithography due to their low physical toughness and high thermal expansion coefficients, we developed stiffer, photocured PDMS silicon elastomers designed, specifically for nano-sized soft lithography and photopatternable nanofabrications.

Thermal expansion coefficients of NH4ReO4and NH4IO4down to 58 K

1985 ◽  
Vol 82 (3) ◽  
pp. 1611-1612 ◽  
Author(s):  
Stanley L. Segel ◽  
H. Karlsson ◽  
T. Gustavson ◽  
K. Edstrom
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

scholarly journals Organizing Cells Within Non-Periodic Microarchitectured Materials That Achieve Graded Thermal Expansions

2015 ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Lucas A. Shaw ◽  
Todd H. Weisgraber ◽  
George R. Farquar ◽  
Christopher D. Harvey ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Large Lattice ◽  
Unit Cells ◽  
Expansion Coefficients ◽  
Bulk Behavior

The aim of this paper is to introduce an approach for optimally organizing a variety of different unit cell designs within a large lattice such that the bulk behavior of the lattice exhibits a desired Young’s modulus with a graded change in thermal expansion over its geometry. This lattice, called a graded microarchitectured material, can be sandwiched between two other materials with different thermal expansion coefficients to accommodate their different expansions or contractions caused by changing temperature while achieving a desired uniform stiffness. First, this paper provides the theory necessary to calculate the thermal expansion and Young’s modulus of large multi-material lattices that consist of periodic (i.e., repeating) unit cells of the same design. Then it introduces the theory for calculating the graded thermal expansions of a large multimaterial lattice that consists of non-periodic unit cells of different designs. An approach is then provided for optimally designing and organizing different unit cells within a lattice such that both of its ends achieve the same thermal expansion as the two materials between which the lattice is sandwiched. A MATLAB tool is used to generate images of the undeformed and deformed lattices to verify their behavior and various examples are provided as case studies. The theory provided is also verified and validated using finite element analysis and experimentation.

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