Heat resistance of aluminide coatings on nickel obtained by mechanochemical heat treatment

1998 ◽  
Vol 40 (10) ◽  
pp. 402-404 ◽  
Author(s):  
V. N. Simonov ◽  
M. A. Khasyanov
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Aluminide Coatings

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.

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.

Preparation of aluminide coatings on the inner surface of tubes by heat treatment of Al coatings electrodeposited from an ionic liquid

2015 ◽  
Vol 101 ◽  
pp. 128-133 ◽  
Author(s):  
Dongpeng Xue ◽  
Yimin Chen ◽  
Guoping Ling ◽  
Kezhao Liu ◽  
Chang’an Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Ionic Liquid ◽  
Aluminide Coatings ◽  
Inner Surface

The Influence of Long-Term Heat Treatment on Microstructure of Zr-Modified Aluminide Coating Deposited by CVD Method on MAR M200+Hf Nickel Superalloy

2013 ◽  
Vol 592-593 ◽  
pp. 469-472 ◽  
Author(s):  
Ryszard Filip ◽  
Marek Góral ◽  
Marcin Zawadzki ◽  
Andrzej Nowotnik ◽  
Maciej Pytel
Keyword(s):  
Heat Treatment ◽  
Aluminide Coating ◽  
Chemical Vapour ◽  
Nickel Superalloy ◽  
Phase Changes ◽  
Vacuum Furnace ◽  
Aluminide Coatings ◽  
Nial Phase ◽  
Main Component

The article presents the investigation of influence of long-term annealing of Zr modified aluminide coatings on its microstructure. The coatings were deposited by Chemical Vapour Deposition on MAR M200+Hf nickel superalloy. Annealing was carried out in a vacuum furnace at the temperature 1020°C within the period of 12, 16 and 20 hours respectively. The microstructral analysis was carried out using Hitachi S-3400 scanning electron microscope. Phase changes in the aluminide layer were observed, particularly the NiAl phase into Ni3Al. Changes in thickness of individual layers in the coating were observed. Conducted research showed that there is no influence of Zr on structure of the aluminide coating during annealing. The structure changes are similar to observed in simple aluminide coating. The maximum time of heat treatment without significant influence on structure of aluminide coating is 16 hours. After that time the main component of coating is NiAl phase.

scholarly journals Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereusSpores

2001 ◽  
Vol 67 (1) ◽  
pp. 317-322 ◽  
Author(s):  
Louis Coroller ◽  
Ivan Leguérinel ◽  
Pierre Mafart
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Water Activity ◽  
Effect Of Water ◽  
Optimal Value ◽  
Negative Effect ◽  
The Difference ◽  
D Values ◽  
Recovery Medium ◽  
Heating Medium

ABSTRACT Spores of Bacillus cereus were heated and recovered in order to investigate the effect of water activity of media on the estimated heat resistance (i.e., the D value) of spores. The water activity (ranging from 0.9 to 1) of the heating medium was first successively controlled with three solutes (glycerol, glucose, and sucrose), while the water activity of the recovery medium was kept near 1. Reciprocally, the water activity of the heating medium was then kept at 1, while the water activity of the recovery medium was controlled from 0.9 to 1 with the same depressors. Lastly, in a third set of experiments, the heating medium and the recovery medium were adjusted to the same activity. As expected, added depressors caused an increase of the heat resistance of spores with a greater efficiency of sucrose with respect to glycerol and glucose. In contrast, when solutes were added to the recovery medium, under an optimal water activity close to 0.98, a decrease of water activity caused a decrease in the estimated D values. This effect was more pronounced when sucrose was used as a depressor instead of glycerol or glucose. When the heating and the recovery media were adjusted to the same water activity, a balancing effect was observed between the protective influence of the solutes during heat treatment and their negative effect during the recovery of injured cells, so that the overall effect of water activity was reduced, with an optimal value near 0.96. The difference between the efficiency of depressors was also less pronounced. It may then be concluded that the overall protective effect of a decrease in water activity is generally overestimated.

Thermal Resistance of Bacillus stearothermophilus Heated at High Temperatures in Different Substrates

1997 ◽  
Vol 60 (2) ◽  
pp. 144-147 ◽  
Author(s):  
F. RODRIGO ◽  
P. S. FERNÁNDEZ ◽  
M. RODRIGO ◽  
M. J. OCIO ◽  
A. MARTÍNEZ
Keyword(s):  
Heat Treatment ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Distilled Water ◽  
Water Acidification ◽  
Mushroom Extract ◽  
Overnight Incubation ◽  
High Temperature Short Time ◽  
Short Time

The effect of mushroom extract, with or without acidification with glucono-δ-lactone, and the overnight incubation of the spores in CaCl2, on the heat resistance of B. stearothermophilus ATCC 12980 spores was studied. The temperature range considered was 121 to 140°C for mushroom extract and CaCl2 and 121 to 145°C for double-distilled water as a reference substrate. The results indicated that mushroom extract without added acid significantly reduces the thermal resistance of the spores in comparison to the double-distilled water. Acidification of the mushroom extract reduces the heat resistance of spores of B. stearothermophilus at 121 °C. However, above 130°C lowering of the pH did not significantly reduce the thermal resistance of the spores, and so no generalizations should be made with regard to the effect of the pH when high temperature-short time (HTST) processes are being considered. Overnight incubation in CaCl2 and subsequent heat treatment lead to increased heat resistance at 121 °C compared to that observed in double-distilled water. However, at 130°C and above CaCl2 did not increase the apparent heat resistance of the spores.

scholarly journals Systematic Assessment of Nonproteolytic Clostridium botulinum Spores for Heat Resistance

2016 ◽  
Vol 82 (19) ◽  
pp. 6019-6029 ◽  
Author(s):  
Ewelina Wachnicka ◽  
Sandra C. Stringer ◽  
Gary C. Barker ◽  
Michael W. Peck
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Heating Process ◽  
Quantitative Microbial Risk Assessment ◽  
Spore Concentration ◽  
Data Set ◽  
Content Type ◽  
Microbial Risk Assessment ◽  
Systematic Assessment ◽  
Value Determination

ABSTRACTHeat treatment is an important controlling factor that, in combination with other hurdles (e.g., pH, aw), is used to reduce numbers and prevent the growth of and associated neurotoxin formation by nonproteolyticC. botulinumin chilled foods. It is generally agreed that a heating process that reduces the spore concentration by a factor of 106is an acceptable barrier in relation to this hazard. The purposes of the present study were to review the available data relating to heat resistance properties of nonproteolyticC. botulinumspores and to obtain an appropriate representation of parameter values suitable for use in quantitative microbial risk assessment. In total, 753Dvalues and 436zvalues were extracted from the literature and reveal significant differences in spore heat resistance properties, particularly those corresponding to recovery in the presence or absence of lysozyme. A total of 503Dand 338zvalues collected for heating temperatures at or below 83°C were used to obtain a probability distribution representing variability in spore heat resistance for strains recovered in media that did not contain lysozyme.IMPORTANCEIn total, 753Dvalues and 436zvalues extracted from literature sources reveal significant differences in spore heat resistance properties. On the basis of collected data, twozvalues have been identified,z= 7°C andz= 9°C, for spores recovered without and with lysozyme, respectively. The findings support the use of heat treatment at 90°C for 10 min to reduce the spore concentration by a factor of 106, providing that lysozyme is not present during recovery. This study indicates that greater heat treatment is required for food products containing lysozyme, and this might require consideration of alternative recommendation/guidance. In addition, the data set has been used to test hypotheses regarding the dependence of spore heat resistance on the toxin type and strain, on the heating technique used, and on the method ofDvalue determination used.

Inactivation of Salmonellae in Autoclaved Ground Beef Exposed to Constantly Rising Temperatures1

1979 ◽  
Vol 42 (5) ◽  
pp. 410-415 ◽  
Author(s):  
W. S. THOMPSON ◽  
F. F. BUSTA ◽  
D. R. THOMPSON ◽  
C. E. ALLEN
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Salmonella Typhimurium ◽  
Clostridium Perfringens ◽  
Constant Temperature ◽  
Ground Beef ◽  
Temperature Data ◽  
Major Influence ◽  
Temperature Work

Inactivation of a composite of five serotypes of salmonellae was monitored in autoclaved ground beef exposed to constantly rising temperatures increased at rates similar to those used in beef cookery. Rising temperature rates of 6.0 C/h, 8.5 C/h and 12.5 C/h and constant temperatures of 55, 57, 61 and 63 C were examined. Survival of Salmonella typhimurium TM-1 was compared to survival of the composite. D and z values were compared for constant and rising temperature rates. The D50 C for constant temperature data was 30.2 min, and the D50 C for changing temperature data was 78.6 min (6.0 C/h), 82.4 min (8.5 C/h), and 49.8 min (12.5 C/h). Neither serotype nor heat treatment of ground beef had a major influence on apparent heat resistance of salmonellae. A comparison of these results to previous rising temperature work with Clostridium perfringens suggested that controlling C. perfringens will result in control of salmonellae. On the basis of these results, the July 18, 1978, USDA processing ruling appears adequate to control salmonellae in precooked beef roasts.

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