scholarly journals The Relationship between the Change in Dynamic Viscoelasticity by Heat Treatment and Heat Resistance in Polystyrene Moldings

2021 ◽  
Vol 70 (1) ◽  
pp. 11-16
Author(s):  
Kousaku TAO ◽  
Koji YAMADA ◽  
Seiji HIGASHI ◽  
Hiroki TAKESHITA ◽  
Katsuhisa TOKUMITSU
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Dynamic Viscoelasticity ◽  
The Relationship

Relationship between Molecular Orientation Relaxation during Physical Aging and Heat Resistance of Polystyrene Injection Moldings

2021 ◽  
Vol 36 (5) ◽  
pp. 577-585
Author(s):  
K. Tao ◽  
K. Yamada ◽  
S. Higashi ◽  
K. Kago ◽  
H. Takeshita ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Molecular Orientation ◽  
Physical Aging ◽  
Core Layer ◽  
Heating Process ◽  
The Core ◽  
Heat Distortion Temperature ◽  
Orientation Relaxation ◽  
The Relationship

Abstract This work examined the relationship between changes in molecular orientation and the heat resistance (heat distortion temperature) of polystyrene injection moldings following heat treatment below the glass transition temperature. Molecular orientation around the core layer of the injection moldings was found to be relaxed by the heat treatment. Also, in the untreated specimen, the molecular orientation around the core layer was relaxed from 60°C during the heating process. Since loss tangent (tanδ) also increased from 60°C during the heating process in the untreated specimen, it was considered that the increase in tanδ occurred with the molecular motion due to the relaxation of molecular orientation from 60°C. After the heat treatment, because of the relaxation of molecular orientation around the core layer by the heat treatment, the relaxation of molecular orientation from 60 °C did not occur during the subsequent heating process, and the tanδ of the polymer between 60 and 90 °C was decreased. Because this decrease in the tanδ over this temperature range improved the heat resistance of the material, the enhanced heat resistance by the heat treatment was attributed to the suppression of the relaxation of molecular orientation from 60°C during the heating process. Furthermore, relaxation of molecular orientation and enthalpy relaxation were related to improvement in the heat resistance.

Structural Defects and Changes in Al-Pd-Fe Crystalline Approximant

2007 ◽  
Vol 26-28 ◽  
pp. 687-690 ◽  
Author(s):  
J.P. Wang ◽  
Wei Sun ◽  
Z. Zhang
Keyword(s):  
Heat Treatment ◽  
High Resolution Electron Microscopy ◽  
Structural Defects ◽  
Decagonal Quasicrystal ◽  
High Temperature Heat Treatment ◽  
Atom Clusters ◽  
Heat Treated ◽  
Resolution Electron ◽  
The Relationship ◽  
Temperature Heat Treatment

Crystalline approximants structurally related to decagonal quasicrystal in the as-cast and heat-treated Al75Pd15Fe10 alloys and defect structures in them have been studied by means of high-resolution electron microscopy (HREM). Structural defects of linear and planar types were found to exist extensively in the orthorhombic ε16-phase formed in the as-cast Al75Pd15Fe10 alloy. In contrast with the distribution and configuration of the defects in the as-cast ε16-phase, we found that high-temperature heat treatment promotes the formation of a kind of regular network of structural defects in the ε16-phase. This suggests that rearrangements of atom clusters and as well as defects occurred due to the heat treatment. The relationship between the distribution of atom clusters and the configuration of defects will be discussed.

Experimental Study on Friction and Wear between Drill Collar and Casing

2016 ◽  
Vol 847 ◽  
pp. 460-465
Author(s):  
Ben Sheng Huang ◽  
Yao Zhu
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Oil And Gas ◽  
Wear Test ◽  
Hardness Test ◽  
Oil And Gas Fields ◽  
Key Issues ◽  
Gas Fields ◽  
The Relationship ◽  
Drill Collar

Casing wear is one of the key issues in the development of oil and gas fields and in the process of drilling operations. In this study, the relationship between hardness and wear resistance of drill collar and casing was studied; thereby the wear conditions between the two materials were improved. Chemical analysis, optical microscopy, hardness test and friction wear test were conducted to study the effects of heat treatment on hardness of the drill collar 4145H and the casing 30Mn5V, and discuss the relationship between hardness and wear resistance of them. The results showed that the materials of drill collar and casing after different heat treatment had varying degrees of wear, both of the respective wear amounts were gradually increasing with the increase of hardness of them, the wear extent of casing material was greater than that of drill collar material. The hardness of casing material was the lowest and its wear resistance was the best when quenching at 880°C and tempering at 630°C. And when quenching at 900°C and tempering at 690°C, the hardness of drill collar material was the lowest and its wear resistance was the best. Therefore, the hardness of drill collar and casing can be improved by changing the heat treatment process to improve the wear resistance, thereby reducing the wear conditions between them.

scholarly journals Carbonitration of a Tool for Pressing Stainless Steel Pipes

2020 ◽  
Vol 7 (2) ◽  
pp. C17-C21
Author(s):  
I. V. Ivanov ◽  
M. V. Mohylenets ◽  
K. A. Dumenko ◽  
L. Kryvchyk ◽  
T. S. Khokhlova ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Heat Resistance ◽  
Alkali Metals ◽  
Matrix Ring ◽  
High Hardness ◽  
Operating Conditions ◽  
Matrix Rings ◽  
Conventional Heat Treatment ◽  
The Stability

To upgrade the operational stability of the tool at LLC “Karbaz”, Sumy, Ukraine, carbonation of tools and samples for research in melts of salts of cyanates and carbonates of alkali metals at 570–580 °C was carried out to obtain a layer thickness of 0.15–0.25 mm and a hardness of 1000–1150 НV. Tests of the tool in real operating conditions were carried out at the press station at LLC “VO Oscar”, Dnipro, Ukraine. The purpose of the test is to evaluate the feasibility of carbonitriding of thermo-strengthened matrix rings and needle-mandrels to improve their stability, hardness, heat resistance, and endurance. If the stability of matrix rings after conventional heat setting varies around 4–6 presses, the rings additionally subjected to chemical-thermal treatment (carbonitration) demonstrated the stability of 7–9 presses due to higher hardness, heat resistance, the formation of a special structure on the surface due to carbonitration in salt melts cyanates and carbonates. Nitrogen and carbon present in the carbonitrided layer slowed down the processes of transformation of solid solutions and coagulation of carbonitride phases. The high hardness of the carbonitrified layer is maintained up to temperatures above 650 °C. If the stability of the needle-mandrels after conventional heat treatment varies between 50–80 presses, the needles, additionally subjected to chemical-thermal treatment (carbonitration) showed the stability of 100–130 presses due to higher hardness, wear resistance, heat resistance, the formation of a special surface structure due to carbonitration in melts of salts of cyanates and carbonates. Keywords: needle-mandrel, matrix ring, pressing, heat treatment, carbonitration.

Influence of Residual Stress on the Thermal Expansion Behavior of Electroformed Nickel Layers

2013 ◽  
Vol 662 ◽  
pp. 511-514
Author(s):  
Yi Chun Liu ◽  
Jia Min Zhang ◽  
Jian Hong Yi
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Theoretical Analysis ◽  
Subsequent Heat Treatment ◽  
Experimental Results ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior ◽  
Electroformed Nickel ◽  
The Relationship

Nickel layers with tensile or pressure residual stress were prepared by electroforming technique from two kinds of electrolyte. Subsequent heat treatment was adopted to get the stress released. The coefficients of thermal expansion (CTEs) were measured with a thermal dilatometer and the relationship between residual stress and the measured CTEs was revealed both from experimental results and theoretical analysis.

Heat Resistance of Escherichia coli in Cow and Buffalo Milk

1980 ◽  
Vol 43 (5) ◽  
pp. 376-380 ◽  
Author(s):  
R. S. SINGH ◽  
B. RANGANATHAN
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Resistance ◽  
Skim Milk ◽  
Buffalo Milk ◽  
Time Interval ◽  
E Coli ◽  
Heat Resistant ◽  
Whole Milk

Three Escherichia coli cultures (0111:B4, 0127:B8 and NP) were selected to study their heat-resistant characteristics when in cow skim, cow whole and buffalo whole milk. The temperatures of heat-treatment included in this study were 50, 55, 60 and 63 C. The time interval during heat-treatment was 10 min at 50 and 55 C and 5 min at 60 and 63 C. Marked differences in heat-resistance were observed in the three E. coli cultures. The z-values obtained for strain 0111:B4 were 8.3, 9.0 and 10.2 when tested in cow skim milk, cow whole milk and buffalo milk, respectively. The z-values for 0127:B8 and NP were 17.5, 18.0 and 19.2 and 18.8, 19.0 and 20.3, respectively, for the three types of milk.

Thermal Inactivation of Listeria monocytogenes in Chicken Gravy

1992 ◽  
Vol 55 (7) ◽  
pp. 492-496 ◽  
Author(s):  
I-PING D. HUANG ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH ◽  
M. EILEEN MATTHEWS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Refrigerated Storage ◽  
Department Of Agriculture ◽  
Large Numbers ◽  
Z Value ◽  
D Values ◽  
The U.S

Heat resistance of Listeria monocytogenes strains V7 and Scott A in chicken gravy and changes in heat resistance during refrigerated storage were studied. After chicken gravy was made, it was cooled to 40°C, inoculated with 105 CFU L. monocytogenes per ml of gravy, and then stored at 7°C for 10 d. Gravy was heated at 50, 55, 60, and 65°C immediately after inoculation and after 1, 3, 5, and 10 d of refrigerated storage. The D values for strains Scott A and V7 in gravy heated at 50°C at day 0 were 119 and 195 min and at day 10 they were 115 and 119 min, respectively, whereas at 65°C comparable values at day 0 were 0.48 and 0.19 min and at day 10 they were 0.014 and 0.007 min. Heat resistance (expressed as D values) was greater at day 0 than at the end of refrigerated storage. The z values ranged from 3.41 to 6.10°C and were highest at the early stages of chill storage and then decreased at the later stages. Strain V7 was more heat resistant than Scott A at 50°C. Strain Scott A always had a higher z value than did strain V7 at the same storage interval. A heat treatment greater than the 4-D process recommended by the U.S. Department of Agriculture was required to inactivate the large numbers of L. monocytogenes that developed in chicken gravy during refrigerated storage.

Growth and Heat Resistance of Clostridium SporogenesPA 3679 Spores Heated and Recovered in Acidified Media

1995 ◽  
Vol 58 (6) ◽  
pp. 656-659 ◽  
Author(s):  
T. SÁNCHEZ ◽  
M. RODRIGO ◽  
M. J. OCIO ◽  
P. FERNÁNDEZ ◽  
A. MARTÍNEZ
Keyword(s):  
Heat Treatment ◽  
Citric Acid ◽  
Heat Resistance ◽  
Medium Composition ◽  
Colony Development ◽  
Medium Ph ◽  
Clostridium Sporogenes ◽  
Ph Level ◽  
Recovery Medium ◽  
Heating Medium

The effect of subculture medium composition (pH, type of acidulant, presence of EDTA) on the germination of spores of Clostridium sporogenes PA 3679, both with and without heat treatment in phosphate buffer (30 s at l25°C), was studied. Additionally, the effect of the heating medium substrate and pH and subculture medium pH and composition on the heat resistance of the spores was evaluated. The results indicate that the pH of the recovery medium and the type of acidulant have significant effects (P ≤ 0.05) on counts of PA 3679. Adding EDTA only increases inhibition of this microorganism when the pH is near neutral. For a given pH level, citric acid provided greater inhibiting power than glucono-δ-lactone, although the percentage of undissociated acid was less for citric acid. No growth was observed at pH 5.7, although in the case of glucono-δ-lactone sporadic colony development was seen in some plates. The pH of the heating medium acidified with glucono-δ-lactone did not affect the heat-resistance parameters (D and z) of spores heated to temperatures between 121 and 140°C in relation to the unacidified extract. Nor did we see any significant influence of the composition and pH of the recovery medium on these heat-resistance parameters when comparing the results with those obtained using the usual recovery medium.

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