Strain variation in the Ti40,7Hf9,5Ni41,8Cu8 alloy during isothermal martensitic transformation under a constant stress

Strain variation on holding under a constant stress was studied in the Ti40,7Hf9,5Ni41,8Cu8 alloy. It was found, that on holding under stress, the isothermal strain rose up to saturation, which value depended on holding temperature and stress. It was found that the dependencies of the isothermal strain on the holding temperature and stress were non-monotonic. This allowed to find the optimal value of stress and time at which the isothermal strain attained the maximum value of 3.2 %. It was found that the maximum isothermal strain in the Ti40,7Hf9,5Ni41,8Cu8 alloy was less than in the Ti40,7Hf9,5Ni44,8Cu5 alloy.

Study of Grain Growth in a Ni-Based Superalloy by Experiments and Cellular Automaton Model

The grain growth behavior in a typical Ni-based superalloy was investigated using isothermal heat treatment experiments over a holding temperature range of 1353–1473 K. The experimental results showed that the grain structure continuously coarsened as the holding time and holding temperature increased during heat treatment. A classical parabolic grain growth model was used to explore the mechanism of grain growth under experimental conditions. The grain growth exponent was found to be slightly above 2. This indicates that the current grain growth in the studied superalloy is mainly governed by grain boundary migration with a minor pinning effect from the precipitates. Then, the grain growth in the studied superalloy during isothermal heat treatment was modelled by a cellular automaton (CA) with deterministic state switch rules. The microscale kinetics of grain growth is described by the correlation between the moving velocity and curvature of the grain boundary. The local grain boundary curvature is well evaluated by a template disk method. The grain boundary mobility was found to increase with increasing temperature. The relationship between the grain boundary mobility and temperature has been established. The developed CA model is capable of capturing the dependence of the grain size on the holding time under different holding temperatures.

Effect of Extender, Storage Time and Temperature on Kinetic Parameters (CASA) on Bull Semen Samples

CASA kinetic parameters are often evaluated in a diagnostic centre. How storage conditions affect ejaculates up to evaluation is unclear. We assessed, in 25 commercial bulls electroejaculated in the field, the impact of time until evaluation (0–2 h, 4–6 h, and 24 h post-ejaculation), holding temperature (5 °C vs. room temperature), and extender (AndroMed®, BIOXcell® or INRA96®) on CASA kinetic parameters. Total and progressive motility, VCL, VAP, VCL, ALH, BCF, STR, LIN, and WOB were assessed. CASA kinetic parameters were preserved for up to 4–6 h post-ejaculation, except for AndroMed®. Regardless of extender or temperature, motility decreased from 4–6 h up to 24 h, with the best values obtained with BIOXcell® at 5 °C. Our results suggest that BIOXcell® can preserve sperm motility for up to 6 h, either at 5 °C or room temperature, and also INRA96® at room temperature, with motility assessments and the percentage of the most rapid sperms being the lowest with INRA96® at 5 °C. The kinetic parameters decreased when analyses were performed at 24 h. Therefore, we suggest evaluating seminal quality as soon as possible, before 6 h after collection. These results help to fix adequate protocols for the short-term storage and shipment of bovine semen collected under field conditions.

Effects of Extender Type, Storage Time, and Temperature on Bull Semen Parameters

Seminal parameters can be evaluated in situ, or samples can be delivered to a diagnostic centre. How storage conditions affect ejaculates up to evaluation is unclear. We assessed, in 25 commercial bulls electroejaculated in the field, the impact of time until evaluation (0–2 h, 4–6 h, and 24 h post-ejaculation), holding temperature (5 °C vs. room temperature), and extender (AndroMed®, BIOXcell® or INRA96®) on semen quality. Acrosome integrity, sperm viability and morphology, CASA-total and progressive motility, pH, and colony-forming units were assessed. Semen quality was preserved for up to 4–6 h post-ejaculation, except for INRA96® at 5 °C. Regardless of extender or temperature, motility decreased from 4 to 6 h up to 24 h, with the best values obtained with BIOXcell® at 5 °C. pH differed from 4 to 6 h up to 24 h, acidifying when stored at room temperature. Microbiological load was stable over time with AndroMed® and BIOXcell®, and increased at room temperature with INRA96®. Our results suggest that AndroMed® and BIOXcell® can preserve semen quality for up to 6 h, either at 5 °C or room temperature, while INRA96® only at room temperature. These results help to fix adequate protocols for short-term storage and shipment of bovine semen collected under field conditions.

Influence of melt treatment parameters on the characteristics of modified cast iron in the metallurgical industry using data mining methods

A study of the effect of holding the cast iron melt at temperatures of 1,300, 1,450 and 1,600 °C for 20, 55 and 90 minutes on the structure and properties of cast iron in a liquid state and after crystallization was carried out. The studies were carried out on samples with a diameter of 30 mm; cast iron containing 3.61–3.75 % carbon, 1.9–2.4 % silicon, 0.03 % manganese, 0.081–0.084 % phosphorus, 0.031–0.039 % sulfur was poured into green-sand molds. The samples were cast from the original cast iron (unmodified), modified with ferrosilicon 75 GOST 1415-93 (FS75), rare-earth metals (REM) and together with the REM+FS75 complex. The structure of cast iron was investigated by optical metallography, electron microscopy and X-ray structural analysis. An increase in the holding temperature and time of the cast iron melt leads to an increase in its hardness. An increase in temperature at a short holding time leads to an increase in strength in the entire investigated temperature range (1,300–1,600 °С). Holding for 90 minutes at a temperature of 1,450 °C corresponds to an extremum, after which, with a further increase in temperature, a sharp drop in strength is observed. The change in the toughness of cast iron is characterized in a similar way

Galling-Free Cold and Warm Forging of Titanium Wires to Flat Plates by SiC-Coated SiC dies

Pure titanium and titanium alloys were difficult to be forged and press-forged because of their easiness in galling to die and punch surfaces during metal forming. β-SiC coated SiC dies were developed to perform a galling free cold forging of pure titanium wire up to the higher reduction of thickness than 50%. Since the thickness of this SiC coating was 4 mm, various cavities and micro-punches were formed into coating by micro-machining. The pure titanium and β-phase titanium alloy wires were employed as a work for cold and warm forging to investigate the effect of flow stress on the forging behavior up to the reduction of thickness by 70% under the controlled holding temperature. The contact interface of β-SiC coating to the work was precisely analyzed to describe the in situ solid lubricating process on the interface. The free carbon agglomerates isolated at the center of contact interface from the carbon supersaturated β-SiC coating, and, worked as a solid lubricant to prevent the β-SiC coating punch and die from galling during forging under high reduction of thickness.

Investigation of Temperature Deformations and Burning of Models from Polymers

The usage of 3D printing technology SLA and DLP is promising for obtaining casting models. The article presents the results of a study of temperature deformations, developing during the burning of models from polymers “Fun to Do Castable Blend”, “Oh-All! Red” and “Orange Fluor”. In the performance of the experiments, photopolymer models were exposed to an impact of isothermal at temperatures from 50 to 330 °C, and their linear dimensions measured; changes developing on their surface were noted. It is shown that, with an increase of the isothermal holding temperature, the models expand first and narrow later. It has been linked to temperature expansion and subsequent decomposition of the photopolymer. It is shown that the casting molds ,obtained with the usied thin-walled hollow casting models from these photopolymers, are destroyed at the stage of their burning.

The holding temperature of blood during a delay to processing can affect serum and plasma protein measurements

Accurate blood-borne biomarkers are sought for diagnosis, prognosis and treatment stratification. Consistent handling of blood is essential for meaningful data interpretation, however, delays during processing are occasionally unavoidable. We investigated the effects of immediately placing blood samples on ice versus room temperature for 1 h (reference protocol), and holding samples on ice versus room temperature during a 3 h delay to processing. Using Luminex multi-plex assays to assess cytokines (n = 29) and diabetes-associated proteins (n = 15) in healthy subjects, we observed that placing blood samples immediately on ice decreased the serum levels of several cytokines, including PAI-1, MIP1-β, IL-9, RANTES and IL-8. During a delay to processing, some analytes, e.g. leptin and insulin, showed little change in serum or plasma values. However, for approximately half of the analytes studied, a delay, regardless of the holding temperature, altered the measured levels compared to the reference protocol. Effects differed between serum and plasma and for some analytes the direction of change in level varied across individuals. The optimal holding temperature for samples during a delay was analyte-specific. In conclusion, deviations from protocol can lead to significant changes in blood analyte levels. Where possible, protocols for blood handling should be pre-determined in an analyte-specific manner.

OPTIMIZATION OF SYNTHESIS PROCESS OF NANOSTRUCTURED CARBIDE-CORUNDUM SILUMIN MODIFIER

A mathematical model is developed for the process of synthesis of nanostructured modifier TiC-Al2O3 by gasphase deposition based on the system of starting materials TiO2-Al-C. To construct the response equation in the form of a polynomial of the second degree, the experiments were carried out in accordance with the model of a rotatable composite plan of the second order with three factors, including 20 experiments. The main factors considered were the isothermal holding temperature T (°C), the isothermal holding time t (s), and the proportion of the chlorinating component Q (wt.%), and as a response function — the proportion of titanium carbide q(TiC) (wt.%) in the composition of the synthesized modifier. The paper describes the results of computational and experimental modeling, from which it can be concluded that to obtain a modifier with the highest content of titanium carbide, the synthesis parameters should be as follows: T = 900–930 °C; t = 2–2.5 h; Q = 4–4.5 wt.%. The resulting TiC-Al2O3 modifier contains 34 wt.% TiC and has a nanostructured structure, with spherical and filamentous particles which diameter does not exceed 100 nm.

Fabrication and Optical Characterization of Polymeric Aspherical Microlens Array Using Hot Embossing Technology

Hot embossing has been widely used in fabricating microlens arrays because of its low cost, high efficiency, and high quality. The process parameters such as molding temperature, molding pressure, and holding temperature affect the microlens array’s replication quality. This work selected the stainless steel S136H tool steel as the mold material to process an aspheric microlens array structure through ultra-precision milling. Polymethyl methacrylate (PMMA) microlens arrays with different surface replication were prepared by controlling the molding temperature, molding pressure, and holding temperature. By analyzing the surface quality, contour replication, and optical imaging of hot-embossed samples, the optimal molding temperature of PMMA for optimal replication of aspheric lens arrays was determined as 130 °C. Besides, the internal elastic recovery of PMMA affected the dimensional accuracy and optical performance of the lens. The results showed that, at the molding pressure of 400 N and the holding temperature of 60 °C, the surface defects were eliminated, and the aspheric lens array had perfect replication with a profile deviation of only 4 μm. The aspheric microlens array with good quality was eventually achieved by these optimal process parameters, which provides a foundation for producing aspheric microlens arrays in a low-cost and high-efficiency way.