scholarly journals Effect of Ni-Cr Alloy Surface Abrasive Blasting on Its Wettability by Liquid Ceramics

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2007
Author(s):  
Weronika Czepułkowska-Pawlak ◽  
Leszek Klimek ◽  
Marcin Makówka ◽  
Emilia Wołowiec-Korecka
Keyword(s):  
Elevated Temperatures ◽  
Contact Angles ◽  
Compressed Air ◽  
Dental Ceramics ◽  
Vacuum Oven ◽  
Variable Parameters ◽  
Abrasive Particles ◽  
Metal Framework ◽  
Selection Of ◽  
Abrasive Blasting

An adequate surface is essential in ensuring a solid bond between the metal and dental ceramics for metal framework wettability. This work is aimed at investigating the effect of variable abrasive blasting parameters on Ni-Cr alloy surface’s ability to be wetted with liquid ceramics at elevated temperatures. One-hundred and sixty-eight samples were divided into 12 groups (n = 14), which were sandblasted using variable parameters: type of abrasive (Al2O3 and SiC), the grain size of the abrasive (50, 110, and 250 µm), and processing pressure (400 and 600 kPa). After treatment, the samples were cleaned in an ultrasonic cleaner and dried under compressed air. Dental ceramics were applied to the prepared surfaces via drops, and the wettability was tested in a vacuum oven at temperatures in the range of 850–1000 °C. The results were statistically analyzed using ANOVA (α = 0.05). For all surfaces, the contact angles were less than 90° at temperatures below 875 °C. For Al2O3, the best wettability was observed for the smallest particles and, for SiC, the largest particles. The ability to wet the surface of a Ni-Cr alloy is related to its sandblasting properties, such as roughness or the percentage of embedded abrasive particles. It should not be the only factor determining the selection of abrasive blasting parameters when creating a prosthetic restoration.

scholarly journals Processing of teeth of saw blades of cotton processing machines with a stream of compressed air with abrasive particles

2021 ◽  
Vol 304 ◽  
pp. 03033
Author(s):  
Illarion Shin ◽  
Zokhir Shodmonqulov ◽  
Sakhrobjon Nazarov ◽  
Nigora Iskandarova
Keyword(s):  
Silicon Carbide ◽  
Wear Resistance ◽  
Surface Layer ◽  
Machining Process ◽  
Compressed Air ◽  
Black Silicon ◽  
Abrasive Particles ◽  
Fiber Separation ◽  
Deformation Hardening ◽  
Abrasive Blasting

In the article, it is presented materials on abrasive blasting of teeth of saw blades of cotton processing machines with particles of black silicon carbide. The micro-profile of the surface, characterized by the height and pitch of irregularities, after microcutting with abrasive particles is able to intensify the process of fiber separation by activating the tank surfaces of the teeth. This machining process is also accompanied by deformation hardening of the surface layer of the teeth, leading to an increase in the wear resistance and durability of the saws.

scholarly journals Improved strategies to efficiently isolate thermophilic, thermotolerant, and heat-resistant fungi from compost and soil

2021 ◽  
Vol 20 (3) ◽  
pp. 325-339
Author(s):  
Frederick Witfeld ◽  
Dominik Begerow ◽  
Marco Alexandre Guerreiro
Keyword(s):  
Elevated Temperatures ◽  
Fungal Species ◽  
Dna Barcodes ◽  
Heat Shock Treatment ◽  
Isolation And Identification ◽  
Heat Resistant ◽  
Heat Stable ◽  
Promising Source ◽  
Culture Dependent ◽  
Selection Of

AbstractThermophilic, thermotolerant and heat-resistant fungi developed different physiological traits, enabling them to sustain or even flourish under elevated temperatures, which are life-hostile for most other eukaryotes. With the growing demand of heat-stable molecules in biotechnology and industry, the awareness of heat-adapted fungi as a promising source of respective enzymes and biomolecules is still increasing. The aim of this study was to test two different strategies for the efficient isolation and identification of distinctly heat-adapted fungi from easily accessible substrates and locations. Eight compost piles and ten soil sites were sampled in combination with different culture-dependent approaches to describe suitable strategies for the isolation and selection of thermophilous fungi. Additionally, an approach with a heat-shock treatment, but without elevated temperature incubation led to the isolation of heat-resistant mesophilic species. The cultures were identified based on morphology, DNA barcodes, and microsatellite fingerprinting. In total, 191 obtained isolates were assigned to 31 fungal species, from which half are truly thermophilic or thermotolerant, while the other half are heat-resistant fungi. A numerous amount of heat-adapted fungi was isolated from both compost and soil samples, indicating the suitability of the used approaches and that the richness and availability of those organisms in such environments are substantially high.

scholarly journals The Surface Condition of Ni-Cr after SiC Abrasive Blasting for Applications in Ceramic Restorations

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5824
Author(s):  
Weronika Czepułkowska-Pawlak ◽  
Emilia Wołowiec-Korecka ◽  
Leszek Klimek
Keyword(s):  
Surface Condition ◽  
Abrasive Particle ◽  
Surface Profile ◽  
Abrasive Particles ◽  
Dental Restorations ◽  
Large Width ◽  
Ceramic Restorations ◽  
The Impact ◽  
Abrasive Size ◽  
Abrasive Blasting

Abrasive blasting is a process widely used in dentistry. One of the uses is the development of metal surfaces for connections with ceramics in fixed prosthetic restorations. The purpose of this paper was to check how the rough surface profile (width, height, and depth on unevenness) impacts the surface’s condition, like its wettability and percentage of stuck abrasives. The Ni-Cr alloy surface was abrasive blasted by silicon carbide with the various pressure parameters (0.2, 0.4, and 0.6 MPa) and abrasive particle sizes (50, 110, and 250 µm). Cleaned surfaces were examined for roughness, wettability, and percentage of stuck abrasive particles on the surface. The surface after abrasive blasting using 110 µm of abrasive size and 0.4 MPa pressure has the best wettability results. The width of unevenness may cause it. When the unevenness has too small or too large width and depth, the fluids may not cover the entire cavities because of locking the air. The surface condition of dental alloys directly affects metal–ceramic connection strength. The knowledge about the impact of the abrasive blasting parameters on the bond strength will allow one to create durable dental restorations.

scholarly journals Recent advances in the electrochemical construction of heterocycles

2014 ◽  
Vol 10 ◽  
pp. 2858-2873 ◽  
Author(s):  
Robert Francke
Keyword(s):  
Heterocyclic Compounds ◽  
Elevated Temperatures ◽  
Ring Formation ◽  
Environmentally Benign ◽  
Heterocyclic Chemistry ◽  
Ambient Conditions ◽  
Recent Developments ◽  
Strong Acids ◽  
Selection Of ◽  
Made In

Due to the fact that the major portion of pharmaceuticals and agrochemicals contains heterocyclic units and since the overall number of commercially used heterocyclic compounds is steadily growing, heterocyclic chemistry remains in the focus of the synthetic community. Enormous efforts have been made in the last decades in order to render the production of such compounds more selective and efficient. However, most of the conventional methods for the construction of heterocyclic cores still involve the use of strong acids or bases, the operation at elevated temperatures and/or the use of expensive catalysts and reagents. In this regard, electrosynthesis can provide a milder and more environmentally benign alternative. In fact, numerous examples for the electrochemical construction of heterocycles have been reported in recent years. These cases demonstrate that ring formation can be achieved efficiently under ambient conditions without the use of additional reagents. In order to account for the recent developments in this field, a selection of representative reactions is presented and discussed in this review.

scholarly journals Selection of the chemical composition of steels and their thermal hardening mode using a computer program

2021 ◽  
pp. 59-65
Author(s):  
D. M. Berdiev ◽  
M. A. Uмаrоvа ◽  
A. A. Yusupov
Keyword(s):  
Wear Resistance ◽  
Chemical Composition ◽  
Computer Program ◽  
Sliding Friction ◽  
Thermal Hardening ◽  
Abrasive Particles ◽  
Density Of Dislocations ◽  
Heat Treated ◽  
Final Tempering ◽  
Selection Of

The relationships between the parameters of the structure of heat‑treated steels and their abrasive wear resistance are established. At all temperatures of the final tempering of hardened steel, there is a direct relationship between its structure parameters (the number of elements in a solid solution, the density of dislocations, the size of cementite particles and the intercementite distance) and wear resistance when sliding friction against loose abrasive particles. A computer program has been developed to select the chemical composition of the steel grade and methods of thermal hardening in order to ensure the required wear resistance.

Testing and Acceptance of Semi-Machined Turbine Rotor Forging Elements

2021 ◽  
Author(s):  
Steve Ingistov ◽  
Douglas Nagy
Keyword(s):  
Elevated Temperatures ◽  
Turbine Rotor ◽  
Third Party ◽  
Test Material ◽  
Acceptance Testing ◽  
Critical Elements ◽  
Reverse Engineer ◽  
Compressive Stresses ◽  
High Integrity ◽  
Selection Of

Abstract Turbine wheels are critical elements and the integrity of their forgings is extremely important. The procurement of wheel forgings utilized oversized outside diameters in order to provide ample amount of material from which test material was cut out. Test specimens were produced in accordance with relevant ASTM standards. Test specimens were divided into three groups; tension, impact and hardness / metallography. Tension and impact tests at sub-zero, room and elevated temperatures were conducted in presence of owner’s inspectors at an independent certified laboratory. Once all specimens passed the tests, the semi-machined forgings were released to the machining facility. Machined forgings were then sent for over-speed tests at sub-zero and elevated temperatures. Over-speed testing under sub-zero temperature was the ultimate test of the forgings. Over-speed testing of the forgings under elevated temperatures served to minimize residual tensile stresses at the bore of the wheel and convert them to beneficial compressive stresses. The above described tests of turbine Elements forging are critical when the owner selects third party producers to reverse engineer and manufacture these elements. This paper details the selection of the tests, the execution of the owner’s acceptance testing program, especially the over-speed tests, and how this helps to ensure the high integrity of critical rotating elements for a mid-size heavy industrial frame gas turbine.

scholarly journals Thermal Degradation of Green and Upgraded Flax Fibres

2001 ◽  
Vol 10 (2) ◽  
pp. 096369350101000 ◽  
Author(s):  
J. George ◽  
E.T.J. Klompen ◽  
T. Peijs
Keyword(s):  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Environmental Scanning Electron Microscopy ◽  
Natural Fibres ◽  
Environmental Scanning ◽  
Flax Fibres ◽  
Glass Fibres ◽  
Potential Matrix ◽  
Thermoplastic Resins ◽  
Selection Of

Over the last couple of years, an increasing amount of research has been dedicated to the use of flax fibres as an environmentally friendly alternative to glass fibres in engineering composites. Because of the relatively poor thermal stability of flax fibres compared to glass fibres, knowledge of the thermal degradation profile of these natural fibres is essential for the selection of potential matrix candidates and/or the development of feasible processing and recycling routes. Especially in combination with thermoplastic resins, composite (re)processing may have a detrimental effect on the mechanical properties of the natural fibres. This study reports on the effect of the exposure of two types of flax fibres, green flax and a new upgraded flax fibre called Duralin, to elevated temperatures using thermogravimetric analysis (TGA), residual strength measurements and environmental scanning electron microscopy (ESEM) studies.

scholarly journals Selection of tomato landraces with high fruit yield and nutritional quality under elevated temperatures

2020 ◽  
Vol 100 (6) ◽  
pp. 2791-2799 ◽  
Author(s):  
Aurelia Scarano ◽  
Fabrizio Olivieri ◽  
Carmela Gerardi ◽  
Marina Liso ◽  
Maurizio Chiesa ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Elevated Temperatures ◽  
Fruit Yield ◽  
Selection Of

scholarly journals Electrochemical Analysis of Ultrathin Polythiolsiloxane Films for Surface Biomodification

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Hao-Chun Chiang ◽  
Rastislav Levicky
Keyword(s):  
Polymer Film ◽  
Thermal Denaturation ◽  
Elevated Temperatures ◽  
Electrochemical Analysis ◽  
Thin Layers ◽  
Optimal Selection ◽  
Dna Duplexes ◽  
Critical Importance ◽  
Solid Supports ◽  
Selection Of

The ability of different crosslinkers to crosslink nanometer thick films of the polymer poly(mercaptopropyl)methylsiloxane (PMPMS), thus stabilizing these films on solid supports, was investigated. The four crosslinkers included 1,11-bismaleimidotriethyleneglycol (BM(PEG)3), tris-(2-maleimidoethyl)amine (TMEA), bismaleimidohexane (BMH), and 1,1′-(methylenedi-4,1-phenylene) bismaleimide (BMDPM). PMPMS films treated with the four crosslinkers were compared in the effectiveness of achieved crosslinking, continuity and stability of the films to rearrangement at elevated temperatures, and modification with single-stranded DNA. The results of electrochemical analyses show that more hydrophilic crosslinkers had difficulty reacting fully with PMPMS thiols, even in these nanometer thin layers. This observation highlights the critical importance of selecting crosslinkers that are chemically compatible. Optimal selection of crosslinker yielded films in which the polymer film was largely incapable of rearranging, even at elevated temperatures, yielding reproducible and stable layers. These results validate use of these supports for applications such as monitoring thermal denaturation of immobilized DNA duplexes.

Wettability and Interfacial Characteristic of Sn-Ag-Cu Solder on Ni Substrates at Elevated Temperatures

2012 ◽  
Vol 554-556 ◽  
pp. 703-708
Author(s):  
Li Kun Zang ◽  
Zhang Fu Yuan Yuan ◽  
Hong Liang Yan ◽  
Xin Xue Li
Keyword(s):  
Integrated Circuits ◽  
Elevated Temperatures ◽  
Sessile Drop ◽  
Triple Line ◽  
Contact Angles ◽  
Sessile Drop Method ◽  
Reactive Wetting ◽  
Ni Substrate ◽  
Eds Analysis ◽  
Interfacial Characteristic

Wettability and interfacial characteristic of the Sn-3.0Ag-0.5Cu/Ni system are investigated by sessile drop method at the temperature range of 503~673K. The reactive wetting processes demonstrate that: contact angles between the solder and Ni substrate decrease as exponential decay and the equilibrium contact angles decrease monotonously with the temperature increasing. Triple-line mobility is enhanced as the temperature increases. Interface of the Sn-3.0Ag-0.5Cu /Ni interface are identified by EPMA and EDS analysis as (Cu,Ni)6Sn5 adjacent to the solder and Ni3Sn4 adjacent to the Ni substrate, respectively. Cu is condensed at the interface, the composition of (Cu,Ni)6Sn5 is (23.16~23.46)Ni- (36.56~37.52) Cu-(39.02~40.27)Sn (atom %). The formation of the (Cu,Ni)6Sn5 IMC was known to greatly improve the reliability of the solder joints in integrated circuits.

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