scholarly journals Comment on the Dependence of R□and Current Noise on Grain Size in Thick Film Resistors (TFR's)

1985 ◽  
Vol 12 (1) ◽  
pp. 59-61 ◽  
Author(s):  
M. Wolf ◽  
F. Müller ◽  
H. Hemschik
Keyword(s):  
Grain Size ◽  
Thick Film ◽  
Volume Fraction ◽  
The Other ◽  
Current Noise ◽  
Heterogeneous Structure ◽  
High Current ◽  
Bulk Resistivity ◽  
Metallic Component ◽  
Other Hand

The heterogeneous structure of TFR's results in high resistivities and high current noise. Accepting models of conduction in TFR's, according to which the resistivity is determined by a resistance independent of bulk-resistivity of a metallic-like component, it will be shown, that R□andCeff*(describing current noise behaviour) increase with d and d3, respectively, when d is the grain size. On the other hand, both quantities depend on the volume fraction of the metallic component in the same manner. This leads to the conclusion, that a general dependence in the formCeff*= f(R□) cannot exist.

scholarly journals Dependence of the Sheet Resistivity and Current Noise Behaviour of the Grain Size and Volume Fraction of Conducting Material in Thick-Film Resistors Experiments

1988 ◽  
Vol 13 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F. Müller ◽  
M. Wolf
Keyword(s):  
Grain Size ◽  
Thick Film ◽  
Electrical Conduction ◽  
Conduction Mechanism ◽  
Volume Fraction ◽  
Experimental Results ◽  
Current Noise ◽  
Sheet Resistivity ◽  
Conducting Material ◽  
Electrical Conduction Mechanism

Experimental results concerning the dependence of the sheet resistivity and the noise coefficient on the grain size and the volume fraction, respectively, of the metallic-like component in Bi2Ru2O7-based thick-film resistors are presented. The results are compared with current models for the electrical conduction mechanism in these resistors.

Modeling Recrystallization for 3D Multi-Pass Forming Processes

2007 ◽  
Vol 558-559 ◽  
pp. 1201-1206 ◽  
Author(s):  
Mihaela Teodorescu ◽  
Patrice Lasne ◽  
Roland E. Logé
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Present Model ◽  
Static Recrystallization ◽  
Volume Fraction ◽  
The Other ◽  
Finite Element Code ◽  
3D Numerical Simulation ◽  
Fraction Distribution ◽  
Simulation Results

The present work concerns the simulation of metallurgical evolutions in 3D multi-pass forming processes. In this context, the analyzed problem is twofold. One point refers to the management of the microstructure evolution during each pass or each inter-pass period and the other point concerns the management of the multi-pass aspects (different grain categories, data structure). In this framework, a model is developed and deals with both aspects. The model considers the microstructure as a composite made of a given (discretized) number of phases which have their own specific properties. The grain size distribution and the recrystallized volume fraction distribution of the different phases evolve continuously during a pass or inter-pass period. With this approach it is possible to deal with the heterogeneity of the microstructure and its evolution in multi-pass conditions. Both dynamic and static recrystallization phenomena are taken into account, with typical Avrami-type equations. The present model is implemented in the Finite Element code FORGE2005®. 3D numerical simulation results for a multi-pass process are presented.

Effects of Solid Volume Fraction on the Gelcasting of Alumina Suspensions

2007 ◽  
Vol 280-283 ◽  
pp. 1041-1044
Author(s):  
Yong Huang ◽  
Li Ming Zhang ◽  
Hai Feng Li ◽  
Tian Ma
Keyword(s):  
Low Temperature ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
The Other ◽  
Sintered Body ◽  
Green Body ◽  
Microstructure And Properties ◽  
Other Hand ◽  
Alumina Suspensions

The effects of solid volume fraction (SVF) on the gelation of alumina suspensions for gelcasting, debonding and sintering of the green body were studied. It was found that with SVF rising, the gelation of alumina suspension delayed; and the strength of green body decreased. On the other hand, high SVF resulted in that polymerized acrylamide split at a relative low temperature. These phenomena manifest that the fast polymerization of monomers in high SVF alumina suspension was inhibited, and the flexibility of the gelcasting was improved. However, Excessive solid volume fraction was prone to a bad rheological behavior of alumina suspension, and deteriorated the microstructure and properties of sintered body.

The Intercorrelation Between Microstructure and Chemicalmechanical Polish of Metal Thin Films

1999 ◽  
Vol 564 ◽  
Author(s):  
Wei-Tsu Tseng ◽  
Ying-Lang Wang
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Removal Rate ◽  
Metal Films ◽  
The Other ◽  
Metal Thin Films ◽  
Other Hand ◽  
Underlying Mechanisms ◽  
Table Speed

AbstractThe correlation between microstructures of Al and W metal thin films and their respective CMP performance is investigated. It is found that CMP removal rate decreases with increasing grain size. In both cases, the textures of the metal films are altered and their resistivity increased after CMP. The phenomenon is more pronounced for polish under a greater down force. The table speed, on the other hand, has only minimum effects on microstructure and resistivity. The possible underlying mechanisms leading to this phenomenon are proposed and their potential impacts on metallization reliability is discussed.

Nucleation Barrier for the Precipitation in Nanosized Al-4wt%Cu Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 3463-3466
Author(s):  
Shan Qing Xu ◽  
Zheng Hong Guo ◽  
T.Y. Hsu
Keyword(s):  
Grain Size ◽  
Homogeneous Nucleation ◽  
Critical Size ◽  
Parent Phase ◽  
The Other ◽  
Nucleation Event ◽  
Initial Concentration ◽  
Cu Alloy ◽  
Nucleation Barrier ◽  
Other Hand

The possibility of Al2Cu( q) precipitation in nanosized Al-4wt%Cu alloy is predicted based on the theory of homogeneous nucleation. The result indicates that the initial concentration of Cu in parent phase has little influence on the nucleation event when the grain size is larger than a critical size. On the other hand, when the grain size is smaller than the critical size, the formation of a stable Al2Cu nucleus will be prohibited completely due to the insufficient initial concentration of Cu.

Metallographic, Structural and Mechanical Characterization of a Low Density Fe-Mn-Al-C Steel Microalloyed with Ti/B in As-Cast and Homogenized Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3971-3978 ◽  
Author(s):  
O.E. Villanueva-Perez ◽  
I. Mejía ◽  
V. García-García ◽  
A. Bedolla-Jacuinde
Keyword(s):  
Grain Size ◽  
Mechanical Characterization ◽  
The Other ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Other Hand ◽  
Average Grain Size ◽  
Cast Condition

ABSTRACTLow density (LD) steels have shown particular characteristics in terms of mechanical properties and microstructure, since they have high strength, high ductility and density reduction up to 18%. On the other hand, the addition of microalloying elements such as Ti and B generate hardening by solid solution and precipitation, as well as grain refinement effect. LD steels generate nano-sized kappa phase precipitated from the austenite matrix, and these advanced steels can reach strength and elongation up to 780 MPa and 60%, respectively. The main objective of this research work is the metallographic, structural and mechanical characterization of a LD steel microalloyed with Ti/B in as-cast and -homogenized conditions. For this purpose a Fe-27Mn-7Al-1.2C (%wt) LD steel microalloyed with Ti/B was melted in a vacuum-induction furnace and cast in metallic mold. LD-Ti/B steel samples were homogenized at 1100 °C during 20, 50, 100, 150 and 200 minutes followed by water quenching. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopy, X-ray diffraction (XRD) and microhardness Vickers testing (HV10), respectively. In general, results showed a typical dendritic microstructure with average grain size of 1256 μm in the as-cast condition. On the other hand, the as-homogenized condition showed an austenitic equiaxial microstructure with average grain size from 164 to 940 μm. Austenite, ferrite and kappa phases were detected by X-ray diffraction (XRD). Also, second-phase particles such as AlN, TiC and MnS were detected by LOM and SEM-EDS analysis. LD steel microalloyed with Ti/B exhibited the highest microhardness Vickers value (235 HV10) in the as-cast condition, whilst in the as-homogenized condition microhardness gradually decreases from 223 to 198 HV10 as holding time increases.

Microstructure and Mechanical Properties of Al-0.5 at.% X (=Si, Ag, Mg) Alloys Highly Deformed by ARB Process

2008 ◽  
Vol 584-586 ◽  
pp. 547-552 ◽  
Author(s):  
Daisuke Terada ◽  
Toshiaki Masui ◽  
Naoya Kamikawa ◽  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Microstructure Evolution ◽  
High Purity ◽  
Uniform Elongation ◽  
Mg Alloys ◽  
The Other ◽  
Other Hand ◽  
The Difference ◽  
Lamellar Boundary

Effect of solid solution elements on microstructure evolution and mechanical properties was investigated using a high purity Al (purity 99.99%) and Al-0.5 at.% X ( X = Si, Ag, Mg ) alloys deformed by accumulative roll bonding (ARB) process up to 7 cycles (equivalent strain of 5.6) at ambient temperature. The ARB-processed high purity Al showed the equiaxed microstructure having mean grain size of 750 nm. On the other hand, the microstructure of the ARB-processed Al-0.5at.%X alloys showed lamellar boundary structures elongated along RD. The mean lamellar boundary spacing significantly differed depending on the alloying elements, which suggested that solute atoms had a significant effect on microstructure evolution. The difference in the grain size was regarded to be caused by the difference in recovery processes in the alloys. The tensile strength of the alloys increased with increasing the number of ARB cycles. In the Al-Si and Al-Ag alloys, the post-uniform elongation increased with increasing the number of the ARB cycles. On the other hand, the elongation of the Al-Mg hardly changed during the ARB process.

Reinforcing Function of Polymer Cords Embedded in Rubber under Compression

1992 ◽  
Vol 20 (4) ◽  
pp. 254-264 ◽  
Author(s):  
X. W. Du ◽  
W. Qu ◽  
Z. M. Wan ◽  
H. Ma ◽  
M. Yao ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Volume Fraction ◽  
Failure Stress ◽  
Experimental Results ◽  
The Other ◽  
Composite Specimen ◽  
Small Range ◽  
Buckling Stress ◽  
Other Hand ◽  
Rubber Composite

Abstract Whether polymer cords embedded in rubber under compression have a reinforcing function is still an important question in the analysis of tire structures. In this paper, on the basis of experimental results, it is confirmed that polymer cords embedded in rubber present some stiffness, thus playing a reinforcing role to a certain extent. When the cord volume fraction in the cord-rubber composite is sufficiently large, the reinforcing function of the polymer cords is so significant that the properties of the cord-rubber composite are mainly influenced by those of the cord. When the compressive stress reaches a certain value, the cord-rubber composite specimen yields by buckling if the cord volume fraction is large enough and the cord angle is within a certain small range. The buckling stress, which may be considered to be a failure stress, decreases with an increase in temperature. On the other hand, the effect of the cord angle on the buckling stress is found to be insignificant.

Effects of Alloying Elements on Physical and Mechanical Properties of Co-Al-W-Based L12/fcc Two-Phase Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1195-1200 ◽  
Author(s):  
Katsushi Tanaka ◽  
Haruyuki Inui
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Lattice Mismatch ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Alloying Elements ◽  
Alloying Element ◽  
Two Phase ◽  
Solvus Temperature ◽  
Other Hand

The changes in the γ’ solvus temperature and the volume fraction of Co-Al-W based alloys with fcc / L12 two-phase microstructures upon alloying with quaternary elements have been investigated. All investigated quaternary elements, except for Fe and Re, increase the γ’ solvus temperatures of Co-Al-W based alloys with varying efficiencies depending on quaternary element. On the other hand, the variation of the γ’ volume fraction with alloying depends on the alloying element. Of the investigated quaternary elements, Ta is found to be the most effective in increasing the γ’ solvus temperature of Co-Al-W based alloys. The lattice mismatch significantly increase upon alloying with Ta of 4at.%, which destroys the coherent cuboidal structure.

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