Metals at High Temperature—Test Procedure and Analysis of Test Data

1933 ◽  
Vol 1 (3) ◽  
pp. 145-148
Author(s):  
Ernest L. Robinson
Keyword(s):  
High Temperature ◽  
Applied Stress ◽  
High Temperatures ◽  
Test Data ◽  
Test Procedure ◽  
Test Results ◽  
Allowable Stress ◽  
Actual Service ◽  
Second Year ◽  
Temperature Test

Abstract Tests on the flow of metals at high temperatures under stresses so small that the resulting distortions are less than one-tenth of 1 per cent show, throughout the duration of tests extending into the second year, continued reductions in rates of flow so that, for such small distortions, it is impossible to associate any particular rate of flow with a corresponding allowable stress. A statement of test results, to be of use, requires in addition to rate of flow and applied stress, certainly a record of total extension and possibly also a record of time elapsed. Furthermore, tests should be made under conditions of stress approximating the conditions of application in actual service.

Fracture and Viscoelastic Behavior of Some Polymers at High Temperatures

2005 ◽  
Vol 297-300 ◽  
pp. 384-389 ◽  
Author(s):  
Keisuke Ishikawa ◽  
Yasuhiro Takaku ◽  
Yasuo Kobayashi
Keyword(s):  
High Temperature ◽  
Applied Stress ◽  
High Temperatures ◽  
Viscoelastic Behavior ◽  
Molecular Structures ◽  
High Temperature Strength ◽  
Creep Life ◽  
Specific Strength ◽  
Mechanical Models ◽  
The Difference

Polymers are vital materials in better performance of specific strength. However their application can be restricted by the lower glass transition temperature, Tg. Some polymers have been developed as engineering plastics for the high temperature applications. We examined the high temperature strength of polymers at constant applied stress. The creep rupture and viscoelastic behavior were scrutinized for PC (polycarbonate) and PMMA (polymethyl methacrylate), which were quite different in the molecular structures. The former contains benzene rings and the latter is a single polymer. Tg is 423 K for PC and 378 K for PMMA. The large difference in the creep behavior was observed near Tg. The creep life strongly depends upon the applied stress just below Tg. The creep life is a function of the applied stress as follows. n life t − µ s . The stress exponent, n depends upon the temperature. Mechanical models were applied to evaluate the viscoelastic properties of the polymers at high temperatures. The viscosity rapidly decreased near Tg , regardless of the smaller decrease in the elastic constant. The results would be due to the difference in the molecular structures. The benzene ring could contribute to the higher resistance against the creep deformation through the higher viscosity.

scholarly journals Laboratory methods for the study of rod mixtures at high temperatures

2021 ◽  
pp. 24-27
Author(s):  
S. V. Koreniugin ◽  
S. L. Rovin
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Laboratory Equipment ◽  
Laboratory Methods ◽  
High Temperature Testing ◽  
Molding Materials ◽  
Temperature Test

The article presents an analysis of laboratory methods for studying temperature and phase expansions and changes in the properties of molding and core mixtures during heating. The analysis of laboratory equipment offered on the Belarusian market for high‑temperature testing of molding materials and mixtures is carried out, the methodology for conducting such tests using devices from leading world manufacturers is described. The results of high‑temperature test tests of mixtures based on furan binders are presented.

Comparison of Several Accelerated Laboratory Tests for the Determination of Localized Corrosion Resistance of High-Performance Alloys

CORROSION ◽  
1983 ◽  
Vol 39 (3) ◽  
pp. 98-102 ◽  
Author(s):  
P. E. Manning
Keyword(s):  
Corrosion Resistance ◽  
High Performance ◽  
Laboratory Tests ◽  
Test Procedure ◽  
Localized Corrosion ◽  
Test Results ◽  
Ferric Ions ◽  
Nickel Base ◽  
Temperature Test

Abstract Results of immersion pitting, immersion crevice, and slow scan potentiodynamic pitting tests are compared to assess the relevance of particular types of accelerated laboratory tests for localized corrosion. The alloys examined include 317 L, 20-type alloys, duplex stainless steels, and nickel-base alloys. The solutions utilized are acid chloride-type with and without ferric ions [Fe2(SO4)3] as an oxidizing species. The acids examined include sulfuric, hydrochloric, and mixtures of these two acids. The best accelerated test for rating localized corrosion resistance of alloys is the immersion pitting temperature test. Results from this test procedure best simulate and correlate with the service performance of alloys.

scholarly journals Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4263
Author(s):  
Marta Dudek ◽  
Mateusz Sitarz
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Test Results ◽  
Spectroscopy Analysis ◽  
Granulated Blast Furnace Slag ◽  
Current State ◽  
High Durability ◽  
Digital Microscope ◽  
Microstructure Of The Material

The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

Pemberian Umpan Balik Dalam Meningkatkan Hasil Belajar dan Minat Belajar Mahasiswa

2015 ◽  
Vol 4 (3) ◽  
Author(s):  
Seruni Seruni ◽  
Nurul Hikmah
Keyword(s):  
Information Technology ◽  
Learning Outcomes ◽  
Test Data ◽  
Random Sampling ◽  
Covariance Matrices ◽  
Test Results ◽  
Immediate Feedback ◽  
Statistics Course ◽  
Independent Variable ◽  
Descriptive Statistical Analysis

<p>The purpose of this study is to find and analyze the effect of feedback on <br />learning outcomes in mathematics and an interest in basic statistics course. The <br />population in this study are affordable Information Technology Student cademic Year 2012/2013 Semester II Indraprasta PGRI University of South Jakarta. Sample The study sample was obtained through random sampling. This study used an experimental method to the analysis using the MANOVA test. This study has three variables, consisting of: one independent variable, namely the provision of feedback (immediate and delayed), and two dependent variable is the result of interest in the study of mathematics and basic statistics course. The data was collected for the test results to learn mathematics, and a questionnaire for the interest in basic statistics course. Collected data were analyzed using the MANOVA test. Before the data were analyzed, first performed descriptive statistical analysis and test data analysis requirements (test data normality and homogeneity of covariance matrices). The results show that the learning outcomes of interest in mathematics and basic statistics course for students who are given immediate feedback higher than students given feedback delayed. <br /><br /></p>

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