Influence of excess silicon phase on the thermal expansion behaviours of Al-Si binary casting alloys

2021 ◽  
pp. 146442072110579
Author(s):  
Zhijun Ma ◽  
Mengge Liu ◽  
Wei Yang ◽  
Zhong Yang ◽  
Yongchun Guo ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Aging Treatment ◽  
Casting Process ◽  
Morphological Transformation ◽  
Silicon Phase ◽  
Excess Silicon ◽  
Casting Alloys ◽  
Before And After ◽  
The Relationship

Al-Si casting alloys are the most commonly used materials for piston alloys. The coefficient of thermal expansion is the key property of a piston material for improving the overall performance and service life of an engine. In the present study, the relationship between the morphology of the excess silicon phase and the coefficient of thermal expansion of Al-Si binary casting alloys was discussed. Optical and scanning electron microscopy were utilized to observe the morphology of the excess silicon phase in the Al-Si binary casting alloys before and after solution aging treatment. The results showed that the morphology of the excess silicon phase significantly influenced the coefficient of thermal expansion of the Al-Si binary casting alloys. After solution aging treatment, the coefficient of thermal expansion of the Al-Si binary casting alloys increased due to the rounding and granulating of the excess silicon phase precipitated during the casting process and decreased due to the precipitation of the finely dispersed Si phase in the α-Al matrix. The change in the coefficient of thermal expansion depended on which of the two kinds of morphological transformation of the excess silicon phase is dominant.

Thermal Expansion and Laser Trim Stability of Ruthenium Based Thick Film Resistors on Alumina and on Multilayer Dielectric

1982 ◽  
Vol 1 (1) ◽  
pp. 24-27 ◽  
Author(s):  
I. Taitl
Keyword(s):  
Thermal Expansion ◽  
Thick Film ◽  
Chemical Structure ◽  
Coefficient Of Thermal Expansion ◽  
Ruthenium Dioxide ◽  
Theoretical Conclusion ◽  
Film Resistor ◽  
Thick Film Resistor ◽  
The Relationship ◽  
Multilayer Dielectric

Fired resistors exhibit variations which are minimised by abrasive and laser trimming. The latter may cause unstable behaviour which is further aggravated by thermal shock. The chemical structure of a thick film resistor is analysed with respect to mechanical stress, and the theoretical conclusion that the coefficient of thermal expansion of the resistor should be equal to or smaller than that of the substrate is verified experimentally. The thermal behaviour of ruthenium dioxide is examined and a range of CTE values are determined for materials of varying chemical composition. The relationship between CTE and post laser trimming stability is demonstrated on four thick film resistors which differ in thermal expansion. It is pointed out that formulations with high metallic content can absorb tensile stress by elastic deformation, thus minimising the formation or propagation of laser induced cracks.

Bi-Material Re-Entrant Triangle Cellular Structures Incorporating Tailorable Thermal Expansion and Tunable Poisson's Ratio1

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Xiaobing He ◽  
Jingjun Yu ◽  
Yan Xie
Keyword(s):  
Thermal Expansion ◽  
Cellular Structure ◽  
Material Selection ◽  
Coefficient Of Thermal Expansion ◽  
Planar Lattice ◽  
Lattice Cell ◽  
Thermoelasticity Equation ◽  
Triangle Lattice ◽  
Temperature Load ◽  
The Relationship

Abstract Based on the bi-material triangle lattice cell, a new cellular structure, bi-material re-entrant triangle (BRT) cellular structure, is devised to incorporate tailorable coefficient of thermal expansion (CTE) and tunable Poisson's ratio (PR) properties by replacing the straight base of a triangle with two hypotenuse members. A general thermoelasticity equation to systematically build the relationship among the external force, the temperature load, and the deformation for planar lattice structures with bounded joints is derived and then embedded into a theoretical model for the devised BRT structure. Using assembled thermoelasticity equation, effective PR, Young's modulus, as well as CTE are computed. In order to guide designers to construct initial concepts, the design domain for coupling negative CTE and negative PR properties is plotted. The material-property-combination region that can be achieved by this cellular structure is determined within an Ashby material selection chart of CTE versus PR. Nine available combinations of CTE and PR properties are extracted and demonstrated with abaqus simulation.

Investigation on Silicon-Glass Electrostatic Bonding Time Experiment

2011 ◽  
Vol 483 ◽  
pp. 78-82
Author(s):  
Xiao Wei Liu ◽  
Jia Lu Tang ◽  
Rong Yan Chuai ◽  
Hai Feng Zhang ◽  
Xi Lian Wang
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Bonding Process ◽  
Bonding Time ◽  
Relationship Of ◽  
The Mathematical Model ◽  
The Relationship ◽  
Electrostatic Bonding

In this paper, we make a detail analysis of some factors, which affects the electrostatic bonding process. According to the electrical properties of glass, combined with the principle of electrostatic bonding, we analysed the relationship of critical bonding time, voltage and temperature as well as the factors which affect electrostatic bonding. Then we come up with the mathematical model of the intensity and temperature of electrostatic bonding. In accordance with the above-mentioned formula and the experimental data, we can get the following conclusions: the intensity of electrostatic bonding is much greater between 280°C to 370°C; the best temperature for this bonding is about 350°C; however, when the temperature is below 280°C,the intensity of electrostatic bonding is lower due to the great impact of particles under low temperature; but when the temperature is higher than 370°C,the mismatch of coefficient of thermal expansion of silicon and glass gets larger, then as a result, the intensity of this bonding has a significant decrease with the increasing of temperature.

Thermal Expansion and Glass Transition Behaviour of Thin Polymer Films with and without a Free Surface Via Neutron Reflectometry

1998 ◽  
Vol 543 ◽  
Author(s):  
D. J. Pochan ◽  
E. K. Lin ◽  
S. Satija ◽  
S. Z. D. Cheng ◽  
Wen-Li Wu
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Free Surface ◽  
Film Thickness ◽  
Coefficient Of Thermal Expansion ◽  
Neutron Reflectometry ◽  
Bilayer Films ◽  
Fluorinated Polyimide ◽  
Expansion Behavior ◽  
Before And After

AbstractThe thermal expansion of thin deuterated polystyrene (dPS) films supported on energetically repulsive, fluorinated polyimide (PI) substrates (PI/dPS bilayer) was measured via neutron reflectometry as a function of initial dPS film thickness. Film thickness was measured before and after capping with a top layer of the same repulsive, high glass transition polyimide that comprised the substrate layer (PI/dPS/PI trilayer) in an attempt to observe any effects of the dPS free surface in the bilayer geometry. Bulk thermal expansion behavior, characterized by a discontinuous change in coefficient of thermal expansion (CTE) at the glass transition (Tg), is observed in films with thickness > 70 rim. For thicknesses between 70 nm and 40 nm a transition is seen from bulk behavior in bilayer films to glassy thermal behavior in the trilayer films persisting up to 20 °C above the bulk Tg. In films with thickness < 40 nm the bulk glassy CTE persists well above the bulk Tg for both bilayer and trilayer films

scholarly journals Influence of cerium content on the microstructure and thermal expansion properties of suction cast Al-Cu-Fe alloys

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Juan Wang ◽  
Zhong Yang ◽  
Zhijun Ma ◽  
Yaping Bai ◽  
Hongbo Duan ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Rare Earth ◽  
Coefficient Of Thermal Expansion ◽  
Casting Process ◽  
Aerospace Materials ◽  
Vacuum Suction ◽  
Suction Casting ◽  
Cerium Content ◽  
Fe Alloys ◽  
Addition Amount

Low-expansion alloys are of great importance and can be used for the development of new aerospace materials. Herein, we report diverse rare earth quasicrystal alloys fabricated by the vacuum suction casting process. The effects of the addition of cerium (Ce) on the microstructure, thermal expansion properties and microhardness of the Al-Cu-Fe alloy were systematically investigated. This study discovered the tiny Al-Cu-Fe-Ce microstructure. A uniform distribution could be achieved after Ce addition amount is elevated. At the Ce addition amount of 1 at%, the lowest alloy thermal expansion coefficient was obtained. The alloy exhibited the maximum microhardness under these conditions. The microhardness of alloys containing 1 at% of Ce was approximately 2.4 times higher than the microhardness exhibited by alloys devoid of Ce additives. The coefficient of thermal expansion decreases by approximately 20%. The use of the suction casting process and the addition of an appropriate amount of Ce can potentially help design and develop Al-Cu-Fe-Ce alloys.

The relationship between bond ionicity, lattice energy, coefficient of thermal expansion and microwave dielectric properties of Nd(Nb1−xSbx)O4 ceramics

2015 ◽  
Vol 44 (24) ◽  
pp. 10932-10938 ◽  
Author(s):  
Ping Zhang ◽  
Yonggui Zhao ◽  
Xiuyu Wang
Keyword(s):  
Thermal Expansion ◽  
Dielectric Properties ◽  
Coefficient Of Thermal Expansion ◽  
Microwave Dielectric Properties ◽  
Semiempirical Method ◽  
Lattice Energy ◽  
Bond Ionicity ◽  
Microwave Dielectric ◽  
Energy Coefficient ◽  
The Relationship

Bond ionicity, lattice energy, and coefficient of thermal expansion were calculated using a semiempirical method.

Synthesis of Copper/Silicon-Carbide Composites in a Thermodynamic Disequilibrium

2015 ◽  
Vol 825-826 ◽  
pp. 189-196 ◽  
Author(s):  
Maren Klement ◽  
Alwin Nagel ◽  
Oliver Lott
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Quantitative Description ◽  
Casting Process ◽  
Heat Sinks ◽  
High Thermal Conductivity ◽  
Structure Property ◽  
Mechanical Loads

Composites with interpenetrating metal-ceramic microstructures (IPC, interpenetrating composites) can be tailored for specific applications, such as high thermal conductivity combined with low thermal expansion, e.g. for heat sinks. Heat sinks are required in power electronic devices or in future fusion reactor technology where extreme conditions and high cyclic thermo-mechanical loads appear. Due to its rigid ceramic backbone IPCs are expected to reveal high thermal stability. Pure silicon carbide exhibits high thermal conductivity, low coefficient of thermal expansion, high corrosion and wear resistance. But it is also known as a very brittle material when mechanical loads are applied. Thus a composite of silicon carbide with ductile and highly conductive copper seems to be a promising new material for a number of applications.This paper reports the synthesis of Cu-SiC composites using a unique high temperature squeeze casting process (HTSC). Microstructural design of SiC-preforms with open porosity and its synthesis progress is reported. Influence of preform properties, temperature, pressure and atmosphere during HTSC were investigated. A qualitative and quantitative description of the microstructure of the composites and their composition allows the creation of structure-property correlations that take effect retroactively to the casting process.

Liquid-exchange processing and properties of SiC–Al composites

1997 ◽  
Vol 12 (7) ◽  
pp. 1785-1789 ◽  
Author(s):  
Leszek Hozer ◽  
Yet-Ming Chiang ◽  
Svetlana Ivanova ◽  
Isa Bar-On
Keyword(s):  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Exchange Process ◽  
Secondary Phase ◽  
Single Edge ◽  
Silicon Phase ◽  
Silicon Carbides ◽  
Beam Technique

In this paper we demonstrate a novel liquid-exchange process to replace a secondary silicon phase in reaction-bonded siliconized silicon carbides (RBSC's) with a ductile metal reinforcement phase. When RBSC is exchanged with pure Al or Al–Si liquid, secondary phase silicon is dissolved and is substituted by Al or Al–Si alloy. The resulting composites show improvements in fracture toughness (single-edge precracked beam technique), with KIC value up to 8.6 Mpa · m1/2, compared to 3–4 MPa · m1/2 in otherwise similar siliconized silicon carbide. Increased fracture strength (four point flexure) was also observed after the liquid exchange process. The processing furthermore allows the coefficient of thermal expansion to be adjusted, and the thermal conductivity increased, for electronic packaging applications.

Bi-Material Re-Entrant Triangle Structures Incorporating Tailorable Thermal Expansion and Tunable Poisson’s Ratio

2019 ◽  
Author(s):  
He Xiaobing ◽  
Xie Yan ◽  
Yu Jingjun
Keyword(s):  
Thermal Expansion ◽  
Poisson’S Ratio ◽  
Coefficient Of Thermal Expansion ◽  
Coupling Effect ◽  
Poisson's Ratio ◽  
Planar Lattice ◽  
Triangle Lattice ◽  
Lattice Material ◽  
The Relationship ◽  
Initial Concept

Abstract Based on the bi-material triangle lattice material, a new cellular structure: bi-material re-entrant triangle (BRT) is devised to incorporate tailorable coefficient of thermal expansion (CTE) and tunable Poisson’s ratio (PR) properties by replacing the straight base of a triangle with two hypotenuse members. An equation to systematically build the relationship among the external force, the temperature increment and the deformation for the planar lattice material with bounded joints is derived and then embedded into a theoretical model for devised BRT structure. Using master stiffness equation, effective PR, effective Young’s modulus as well as effective CTE are computed. In order to guide designers to construct an initial concept quickly, the design domain for coupling negative CTE and negative PR properties is proposed. Nine available paired characteristics for coupling effect are extracted and demonstrated with ABAQUS simulation.

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