scholarly journals New Opportunities to Determine the Rate of Wear of Materials at Friction by the Indentation Data

2020 ◽  
Vol 21 (4) ◽  
pp. 554-579
Author(s):  
Yu. V. Milman ◽  
B. M. Mordyuk ◽  
K. E. Grinkevych ◽  
S. I. Chugunova ◽  
I. V. Goncharova ◽  
...  
Keyword(s):  
Wear Rate ◽  
Yield Stress ◽  
General Scheme ◽  
Hard Alloys ◽  
Laser Heat Treatment ◽  
Tool Steels ◽  
Surface Layers ◽  
Experimental Part ◽  
Aisi D2

The article is concerned with the determination of physical plasticity δH (the ratio of the plastic strain to the total strain) and yield stress σS by indentation and the application of these characteristics for analysis of the wear rate W during the friction. The experimental part of the work is performed on the AISI O2 and AISI D2 steels, the surface layers of which were hardened by combined thermomechanical treatment consisted of sequential use of laser heat treatment and ultrasonic impact treatment. For the metals, W is shown to be proportional to δH and inversely proportional to σS. The general scheme for the dependence of W on δH is proposed and based on experimental results for tool steels and hard alloys. For the steels, whose wear is caused by the plastic deformation, W increases with increasing δH, and it decreases conversely for hard alloys worn predominantly by the fracture mechanism. The use of physical plasticity δH and yield stress σS, which are calculated using the hardness and Young’s modulus, characterizes both the hardening extent and the wear rate of the surface layers in more full measure and more accurately than the hardness magnitude itself.

scholarly journals Recatest—A Technique for Qualitative and Quantitative Assessment of Deferment and Degraded PVD Coatings and CVD Layers in the Deformed Area in the Scratch Test

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2625
Author(s):  
Piotr Domanowski ◽  
Marek Betiuk
Keyword(s):  
Scratch Test ◽  
Metallographic Analysis ◽  
Tool Steels ◽  
Test Device ◽  
Coating Structure ◽  
Testing Technique ◽  
Coating Materials ◽  
Qualitative And Quantitative ◽  
Quantitative Parameters

The purpose of the paper is to present a new Recatest testing technique which uses a series of abrasions within a scratch and its innovative application to describe selected quantitative parameters of locally, plastically deformed substrate and coating materials detected on the spherical microsection in the scratch test. The exposed material structures are subject to a metallographic analysis which allows for the determination of the quantitative parameters, which in turn allow for a description of the change in dynamics of the coating structure within the scratch area as a function of load. These parameters include scratch depth (hs), coating thickness (h1), flash height (hoc, hos), depth of intended material (hd), material depth under scratch (hcp), and material depth under coating (hdb). The paper also includes a description of the Recalo test device designed by the authors, which is used to make a series of spherical abrasion traces on the scratch surface. Recalo is dedicated to the Recatest technique. The analysed material was the CrN/CrCN/HS6-5-2, AlCrN -Alcrona-Balinit/D2 coatings deposited on tool steels.

Determination of Steady-State Adhesive Wear Rate

2005 ◽  
Author(s):  
L. J. Yang
Keyword(s):  
Steady State ◽  
Wear Rate ◽  
Wear Test ◽  
Standard Test ◽  
Test Method ◽  
Testing Time ◽  
Wear Coefficient ◽  
Wear Rates ◽  
Test Methodology

Wear rates obtained from different investigators could vary significantly due to lack of a standard test method. A test methodology is therefore proposed in this paper to enable the steady-state wear rate to be determined more accurately, consistently, and efficiently. The wear test will be divided into four stages: (i) to conduct the transient wear test; (ii) to predict the steady-state wear coefficient with the required sliding distance based on the transient wear data by using Yang’s second wear coefficient equation; (iii) to conduct confirmation runs to obtain the measured steady-state wear coefficient value; and (iv) to convert the steady-state wear coefficient value into a steady-state wear rate. The proposed methodology is supported by wear data obtained previously on aluminium based matrix composite materials. It is capable of giving more accurate steady-state wear coefficient and wear rate values, as well as saving a lot of testing time and labour, by reducing the number of trial runs required to achieve the steady-state wear condition.

Near earthquakes in Central California*

1939 ◽  
Vol 29 (3) ◽  
pp. 427-462 ◽  
Author(s):  
Perry Byerly
Keyword(s):  
Least Squares ◽  
Travel Time ◽  
Sierra Nevada ◽  
Accurate Determination ◽  
Depth Of Focus ◽  
Surface Layers ◽  
P Waves ◽  
Central California ◽  
The Waves

Summary Least-squares adjustments of observations of waves of the P groups at central and southern California stations are used to obtain the speeds of various waves. Only observations made to tenths of a second are used. It is assumed that the waves have a common velocity for all earthquakes. But the time intercepts of the travel-time curves are allowed to be different for different shocks. The speed of P̄ is found to be 5.61 km/sec.±0.05. The speed for S̄ (founded on fewer data) is 3.26 km/sec. ± 0.09. There are slight differences in the epicenters located by the use of P̄ and S̄ which may or may not be significant. It is suggested that P̄ and S̄ may be released from different foci. The speed of Pn, the wave in the top of the mantle, is 8.02 km/sec. ± 0.05. Intermediate P waves of speeds 6.72 km/sec. ± 0.02 and 7.24 km/sec. ± 0.04 are observed. Only the former has a time intercept which allows a consistent computation of structure when considered a layer wave. For the Berkeley earthquake of March 8, 1937, the accurate determination of depth of focus was possible. This enabled a determination of layering of the earth's crust. The result was about 9 km. of granite over 23 km. of a medium of speed 6.72 km/sec. Underneath these two layers is the mantle of speed 8.02 km/sec. The data from other shocks centering south of Berkeley would not fit this structure, but an assumption of the thickening of the granite southerly brought all into agreement. The earthquakes discussed show a lag of Pn as it passes under the Sierra Nevada. This has been observed before. A reconsideration of the Pn data of the Nevada earthquake of December 20, 1932, together with the data mentioned above, leads to the conclusion that the root of the mountain mass projects into the mantle beneath the surface layers by an amount between 6 and 41 km.

Surface Layers of Structural and Tool Steels Produced by Laser Alloying with Carbide-Forming Elements and Boron

2021 ◽  
Vol 41 (7) ◽  
pp. 598-603
Author(s):  
G. N. Gavrilov ◽  
P. L. Zhilin ◽  
A. V. Bratukhin ◽  
K. V. Razheva ◽  
I. E. Illarionov ◽  
...  
Keyword(s):  
Laser Alloying ◽  
Tool Steels ◽  
Surface Layers

Determination of Yield Stress in a Duplex Steel with α + γ Lamellar Structure

2018 ◽  
Vol 50 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Yoon-Uk Heo ◽  
Joo-Hee Kang ◽  
Nam Hoe Heo ◽  
Sung-Joon Kim
Keyword(s):  
Yield Stress ◽  
Lamellar Structure ◽  
Duplex Steel

scholarly journals THE ELASTO-VISCOPLASTIC-TIME-DEPENDENT NATURE OF WAXY CRUDE OILS

2014 ◽  
Vol 13 (2) ◽  
pp. 16
Author(s):  
B. A. Tarcha ◽  
B. P. P. Forte ◽  
E. J. Soares ◽  
R. L. Thompson
Keyword(s):  
Yield Stress ◽  
Crude Oils ◽  
Time Dependency ◽  
Gelation Temperature ◽  
Viscous Effects ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Crucial Feature ◽  
Waxy Crude Oils

Production in reservoirs located in deep and ultra-deep water that contain waxy crude oils faces a huge obstacle imposed by the low temperatures of the environment. When the waxy crude oil is subjected to a temperature below the Gelation Temperature, as in the case investigated in the present work, it exhibits a variety of non-Newtonian features: elasticity, plasticity, viscous effects, and time-dependency, which renders to this material a highly complex behavior. A crucial feature that is frequently ignored when the determination of the yield stress is being carried out is the timedependency nature of these materials. We demonstrate that this character has a significant impact on the measurement of the yield stress and, therefore, values obtained from a protocol that neglects time-dependency can be substantially different from a more careful procedure.

scholarly journals Evaluation of the suitability of synthetic polymer fuels in self-ignition engines

2019 ◽  
Vol 178 (3) ◽  
pp. 129-134
Author(s):  
Oleh KLYUS ◽  
Paweł KRAUSE ◽  
Vladimir MARKOV ◽  
Anna SKARBEK-ŻABKIN ◽  
Bowen SA
Keyword(s):  
Volume Fraction ◽  
Synthetic Polymer ◽  
Polymer Materials ◽  
Physical Parameters ◽  
Sauter Mean Diameter ◽  
Synthetic Fuels ◽  
Limit Values ◽  
Experimental Part

The article presents a method for determining the quality of spraying a mixture of oil and synthetic fuels obtained from the pro-cessing of polymer materials. Laboratory tests of physical parameters of such a mixture were carried out, which made it possible to determine the limit values for the volume fraction of synthetic fuels. The method of determining the suitability of this type of fuel takes into account the criterion numbers Re and Oh, which include physical parameters such as viscosity, density, and surface tension. The experimental part concerning the distribution of droplets of injected fuel and determination of Sauter Mean Diameter using laser diffrac-tion confirmed the usefulness of the developed method for the assessment of the possibility of using a mixture of petroleum-based and synthetic fuels in self-ignition engines.

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