scholarly journals New approach of friction AlN ceramics metallization with the initial FEM verification

2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Robert Cacko ◽  
Tomasz Chmielewski ◽  
Michał Hudycz ◽  
Dariusz Golański
Keyword(s):  
Chemical Potential ◽  
Potential Gradient ◽  
Substrate Material ◽  
Temperature Fields ◽  
Titanium Coating ◽  
Diffusion Phenomena ◽  
Friction Method ◽  
Short Time ◽  
Time Of Operation ◽  
Metallization Process

Abstract Although, the friction method is well known for metals surface modification, the novelty of the article is based on the new idea of ceramics surface treatment with metal. The paper describes AlN ceramic metallization process by titanium coating deposition, obtained in friction surfacing method, which has been developed by the authors. The friction energy is directly transformed into heat and delivered in a specified amount precisely to the joint being formed between the metallic layer and the ceramics substrate material. The stress and temperature fields (as factors promoting the formation of diffusion joints) induced in the joint during the metallization process were qualitatively determined with the finite element method analysis and these results were verified experimentally. Finally, obtained structures of the metallic coatings were investigated and the results are discussed in the paper. As a novelty it was found, that the conditions of frictional metallization can favour the formation of a coating-substrate bond based on diffusion phenomena and atomic bonds of the coating components with the components of the substrate, despite the fact that it happens for metal–ceramics pairs. This type of connection is usually associated with long-term heating/annealing in chamber furnaces, because for diffusion in a solid state the most effective factor is time and temperature. It was shown that other components of the chemical potential gradient, such as temperature gradient, gradient and stress level, load periodicity and configuration of pairs of elements with high chemical affinity may play an important role in friction metallization. As a result, the relatively short time of operation (friction) is compensated.

scholarly journals Utilizing the energy of kinetic friction for the metallization of ceramics

2015 ◽  
Vol 63 (1) ◽  
pp. 201-207 ◽  
Author(s):  
T. Chmielewski ◽  
D. Golański ◽  
W. Włosiński ◽  
J. Zimmerman
Keyword(s):  
Finite Element Method ◽  
Friction Welding ◽  
Ceramic Materials ◽  
Substrate Material ◽  
Temperature Fields ◽  
Kinetic Friction ◽  
The Finite Element Method ◽  
Welding Method ◽  
Friction Energy ◽  
Metallization Process

Abstract The paper is concerned with the metallization of ceramic materials using the friction-welding method in which the mechanism of the formation of a joint involves the kinetic energy of friction. The friction energy is directly transformed into heat and delivered in a specified amount precisely to the joint being formed between the metallic layer and the substrate material. The paper describes the ceramic metallization process, which has been developed by the present authors based on the friction-welding method. The stress and temperature fields induced in the joint during the metallization process were determined using the finite element method with the aim to optimize the process parameters. The results were verified experimentally. The structures of the metallic coatings thus obtained were examined and the results are discussed in the paper.

Thermally Induced Instability of Laminated Beams and Plates

1996 ◽  
Vol 63 (4) ◽  
pp. 884-890 ◽  
Author(s):  
A. Tylikowski ◽  
R. B. Hetnarski
Keyword(s):  
Stochastic Stability ◽  
Direct Method ◽  
Wide Band ◽  
Temperature Fields ◽  
Time And Space ◽  
Thermally Induced ◽  
Stability Problems ◽  
Linear Elastic ◽  
Liapunov Direct Method ◽  
Short Time

A theoretical investigation of dynamic stability for linear elastic structures due to non-uniform, time and space-dependent stochastic temperature fields is presented. The study is based on the reformulation of stochastic stability problems as a stability of Itoˆ type equations in some appropriate Hilbert space and is adopted for stability problems of structures with time and space-dependent stochastic coefficients. Uniform stochastic stability criteria of the structure equilibrium are derived using the Liapunov direct method. The energy-like functional and the generalized ltoˆ lemma are used to derive the sufficient stability conditions of the equilibrium state. A symmetrically laminated crossply plate subjected to the wide-band Gaussian temperature distribution and a laminated beam subjected to local short-time heatings are analysed in detail.

scholarly journals Research of the influence of spare parts quality on the work of a repair diesel engine

2021 ◽  
Vol 46 (2) ◽  
pp. 38-55
Author(s):  
Vojislav Krstić ◽  
Božidar Krstić
Keyword(s):  
Diesel Engine ◽  
Test Bench ◽  
Internal Combustion ◽  
Spare Parts ◽  
Engine Failure ◽  
Short Time ◽  
Time Of Operation

When repairing the internal combustion Diesel engine, a set of spare parts was installed: crankshaft-flywheel. After the overhauol, the engine was tested on a test bench. After a very short time of operation, an engine failure occurred. Re-overhaul was started, with another set of spare parts: crankshaft-flywheel. After a short time of operation, there were recurrences of engine failures, according to the same mechanisms of occurrence.

scholarly journals The influence of elastic deformations in high-strength structural materials on the hydrogen transport

2021 ◽  
Vol 225 ◽  
pp. 01010
Author(s):  
Polina Grigoreva ◽  
Elena Vilchevskaya ◽  
Vladimir Polyanskiy
Keyword(s):  
Chemical Potential ◽  
Potential Gradient ◽  
Elastic Solid ◽  
High Strength ◽  
Ideal Gas ◽  
Linear Elastic ◽  
Coupled Diffusion ◽  
Elastic Boundary ◽  
Linear Effects ◽  
Solid System

In this work, the diffusion equation for the gas-solid system is revised to describe the non-uniform distribution of hydrogen in steels. The first attempt to build a theoretical and general model and to describe the diffusion process as driven by a chemical potential gradient is made. A linear elastic solid body and ideal gas, diffusing into it, are considered. At this stage, we neglect any traps and non-linear effects. The coupled diffusion-elastic boundary problem is solved for the case of the cylinder under the tensile loads. The obtained results correspond to the experimental ones. Based on them, the assumptions about the correctness of the model and its further improvement are suggested.

Disequilibrium 3: Internal Variables

1993 ◽  
Author(s):  
Brian Bayly
Keyword(s):  
Vinyl Chloride ◽  
Chemical Potential ◽  
Potential Gradient ◽  
Material Behavior ◽  
Internal Variables ◽  
Starting State ◽  
Separate Point ◽  
Point To Point ◽  
New Location ◽  
Rate Of Response

In Chapters 2, 3, and 4, the usefulness of the concept chemical potential has been explored for describing and predicting movement of material from point to point in space—from a location where a component's potential is high to a location where its potential is lower. But chemical potential influences another type of material behavior as well, as in the example at the end of Chapter 2, the polymerization of vinyl chloride. The polymerization is a process that runs at a certain rate, like diffusion of salt, and the rate depends on the potential difference between the starting state and the end state; but unlike diffusion of salt, there is no overall movement from one location to a new location—the vinyl chloride simply polymerizes where it is. There are movements, of course, on the scale of the interatomic distances, but nothing corresponding to the 4 m of travel that appears in the discussion of the dike. If no travel is involved, it is not so easy to calculate a potential gradient along the travel path and go on to predict a rate of response. Yet there definitely is a rate of response, even with PVC polymerizing. The purpose of this chapter is to consider this matter; we shall then be equipped to begin considering nonhydrostatic conditions. The essential idea is to represent all possible degrees of polymerization along an axis, as in Figure 5.1. The figure is drawn to represent a condition where the chemical potential per kilogram is greater in the monomer form than in the dimer form, i.e., a condition where the material polymerizes spontaneously. Suppose we know the chemical potential per kilogram for all degrees of polymerization and also, at some temperature, the rates at which 2 forms from 1, 3 forms from 2, etc. (per kg of the starting form in a pure state). Then we arbitrarily pick a distance on the horizontal axis to separate point 1 from point 2.

Active sodium transport in toad bladder despite removal of serosal potassium

1965 ◽  
Vol 208 (2) ◽  
pp. 401-406 ◽  
Author(s):  
Alvin Essig
Keyword(s):  
Sodium Transport ◽  
Chemical Potential ◽  
Potential Gradient ◽  
Ringer Solution ◽  
Active Sodium ◽  
Chemical Potential Gradient ◽  
Control Value ◽  
Active Sodium Transport ◽  
Solution Bathing ◽  
Determining Factor

Previous studies have demonstrated that removal of potassium from sodium-Ringer solution bathing the serosal surface of the toad badder depressed net sodium transport to some 5% of control value, whereas with choline-Ringer solution as serosal medium removal of serosal potassium depressed net sodium transport only to some 55% of control value. Although transport is down a chemical potential gradient in the latter situation, it appears to be an active process, for it is depressed by anaerobiosis, and persists against an electrochemical potential gradient. The data suggest that the concentration of potassium at the serosal aspect of the sodium pump is not in itself the rate-determining factor for active sodium transport following removal of serosal potassium.

Microstructures and Growth Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by Transmission Electron Microscopy

2007 ◽  
Vol 26-28 ◽  
pp. 1207-1210
Author(s):  
Hyung Seok Kim ◽  
Ju Hyung Suh ◽  
Chan Gyung Park ◽  
Sang Jun Lee ◽  
Sam Kyu Noh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Chemical Potential ◽  
Early Stage ◽  
Compressive Strain ◽  
Potential Gradient ◽  
Growth Direction ◽  
Transmission Electron ◽  
Self Assembled

The microstructure and strain characteristics of self-assembled InAs/GaAs quantum dots (QDs) were studied by using transmission electron microscopy. Compressive strain was induced to uncapped QDs from GaAs substrate and the misfit strain largely increased after the deposition of GaAs cap layer. Tensile strain outside QD was extended along the vertical growth direction; up to 15 nm above the wetting layer. Vertically nonaligned and aligned stacked QDs were grown by adjusting the thickness of GaAs spacer layers. The QDs with a lens-shaped morphology were formed in the early stage of growth, and their apex was flattened by the out-diffusion of In atoms upon GaAs capping. However, aligned QDs maintained their lens-shaped structure with round apex after capping. It is believed that their apex did not flatten because the chemical potential gradient of In was relatively low due to the adjacent InAs QD layers.

scholarly journals Hard Cladding by Supersolidus Liquid Phase Sintering: An Experimental and Simulation Study on Martensitic Stainless Steels

2020 ◽  
Vol 51 (11) ◽  
pp. 5818-5835
Author(s):  
P. K. Farayibi ◽  
M. Blüm ◽  
S. Weber
Keyword(s):  
Liquid Phase ◽  
Stainless Steels ◽  
Chemical Potential ◽  
Interfacial Strength ◽  
Potential Gradient ◽  
Steel Powder ◽  
Liquid Phase Sintering ◽  
Dimple Rupture ◽  
Martensitic Stainless Steels ◽  
Structural Applications

Abstract Martensitic stainless steels are suitable for diverse structural applications but degrade when subjected to wear-prone activities in service. To enhance their service life, the densification of high Cr, martensitic, X190CrVMo20-4-1 tool steel powder on two different martensitic stainless steel substrates via supersolidus liquid-phase sinter (SLPS) cladding was investigated. The objective was to assess the influence of the difference in compositions of the martensitic stainless steels employed as substrates on the interfacial diffusion, microstructure, hardness and bonding strength of the steel-to-steel claddings. Computational thermodynamics and diffusion simulations were employed to supplement experimental findings. Owing to interdiffusion, a M7C3 carbide-free, banded region exists in the X190 adjacent to the interface with the width dictated by chemical potential gradient of carbon. The hardness of the substrate was lower near the interface region because of carbon enrichment, which promoted the presence of retained austenite. An interfacial strength of 798 MPa was achieved with fairly ductile X190 matrix near the cladding interface as the fracture surface was characterized by mixed fracture modes of dimple rupture and cleavage with localized quasi-cleavage features. Experimental observations and computational simulations are in agreement. The implications of the SLPS cladding technique are discussed in the context of tool development.

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