scholarly journals High Temperature Adiabatic Heating in µ-IM Mould Cavities—A Case for Venting Design Solutions

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 358
Author(s):  
Matthew Tucker ◽  
Christian A. Griffiths ◽  
Andrew Rees ◽  
Gethin Llewelyn
Keyword(s):  
High Temperature ◽  
Mass Production ◽  
Extreme Temperature ◽  
Processing Parameters ◽  
Adiabatic Heating ◽  
Fabrication Method ◽  
Production Scale ◽  
Micro Injection Moulding ◽  
Physical Experiments ◽  
Mould Cavity

Micro-injection moulding (µ-IM) is a fabrication method that is used to produce miniature parts on a mass production scale. This work investigates how the process parameter settings result in adiabatic heating from gas trapped and rapidly compressed within the mould cavity. The heating of the resident air can result in the diesel effect within the cavity and this can degrade the polymer part in production and lead to damage of the mould. The study uses Autodesk Moldflow to simulate the process and identify accurate boundary conditions to be used in a gas law model to generate an informed prediction of temperatures within the moulding cavity. The results are then compared to physical experiments using the same processing parameters. Findings from the study show that without venting extreme temperature conditions can be present during the filling stage of the process and that venting solutions should be considered when using µ-IM.

Feasibility Study of a New Fabrication Method for the Li4SiO4 Pebbles

2018 ◽  
Author(s):  
R. Lo Frano ◽  
M. Puccini ◽  
E. Stefanelli ◽  
M. Luppichini ◽  
C. Grima ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Power Reactor ◽  
Fabrication Method ◽  
Fusion Power ◽  
Spray Process ◽  
The Past ◽  
Experimental Apparatus ◽  
Standard Solution ◽  
Lithium Orthosilicate

In the past decades many R&D efforts have been spent in the development of a suitable Li4SiO4 fabrication method (e.g., melt spray process, graphite bed method, capillary-based microfluidic wet method etc.), nevertheless we are still far from an “industrial standard solution”. The aim of the paper is to develop a new fabrication method capable to produce stable and well-sized pebbles of lithium orthosilicate (Li4SiO4) based on the drip casting. This method is mainly based on the dripping at room temperature, which is novel in the framework of available fabrication processes requiring high temperature: this latter is demonstrated to affect the final product characteristics. It is worthy to remark that the Li4SiO4 is a candidate material for the breeding blanket material of the fusion power reactor. In the paper we will describe the experimental apparatus, designed and built at DICI - University of Pisa with the collaboration of Bitossi Industries, and the procedure adopted in order to produce pebbles of Li4SiO4.

Influence of Processing Parameters and Different Content of Tib2 Ceramics on the Properties of Composites Sintered by High Pressure -High Temperature (HP-HT) Method

2014 ◽  
Vol 59 (1) ◽  
pp. 205-209 ◽  
Author(s):  
I. Sulima ◽  
L. Jaworska ◽  
P. Figiel
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Processing Parameters ◽  
Structure Changes ◽  
High Pressure High Temperature ◽  
Mechanical And Physical Properties ◽  
Temperature And Pressure ◽  
Different Content ◽  
Scanning Electron ◽  
Properties Of Composites

Abstract In this paper the properties of the austenitic stainless steel reinforced with various volume fractions of TiB2 ceramics have been studied. The high pressure- high temperature (HP-HT) method of sintering was applied to the formation of composites. Samples were sintered at pressure of 5 and 7 ±0.2 GPa and temperatures of 1273 K and 1573 K. For the tested materials, the relative density, Young’s modulus and hardness were measured. In order to investigate the structure changes, the scanning electron microscope was used. The obtained results show that the temperature and pressure influence on the mechanical and physical properties of the investigated composites.

scholarly journals Dynamics of Microbial Inactivation and Acrylamide Production in High-Temperature Heat Treatments

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2535
Author(s):  
Jose Lucas Peñalver-Soto ◽  
Alberto Garre ◽  
Arantxa Aznar ◽  
Pablo S. Fernández ◽  
Jose A. Egea
Keyword(s):  
High Temperature ◽  
Food Safety ◽  
High Temperatures ◽  
Processing Parameters ◽  
Temperature Treatment ◽  
Heat Treatments ◽  
Microbial Inactivation ◽  
Point Of View ◽  
High Temperature Treatment ◽  
Microbiological Safety

In food processes, optimizing processing parameters is crucial to ensure food safety, maximize food quality, and minimize the formation of potentially toxigenic compounds. This research focuses on the simultaneous impacts that severe heat treatments applied to food may have on the formation of harmful chemicals and on microbiological safety. The case studies analysed consider the appearance/synthesis of acrylamide after a sterilization heat treatment for two different foods: pureed potato and prune juice, using Geobacillus stearothermophilus as an indicator. It presents two contradictory situations: on the one hand, the application of a high-temperature treatment to a low acid food with G. stearothermophilus spores causes their inactivation, reaching food safety and stability from a microbiological point of view. On the other hand, high temperatures favour the appearance of acrylamide. In this way, the two objectives (microbiological safety and acrylamide production) are opposed. In this work, we analyse the effects of high-temperature thermal treatments (isothermal conditions between 120 and 135 °C) in food from two perspectives: microbiological safety/stability and acrylamide production. After analysing both objectives simultaneously, it is concluded that, contrary to what is expected, heat treatments at higher temperatures result in lower acrylamide production for the same level of microbial inactivation. This is due to the different dynamics and sensitivities of the processes at high temperatures. These results, as well as the presented methodology, can be a basis of analysis for decision makers to design heat treatments that ensure food safety while minimizing the amount of acrylamide (or other harmful substances) produced.

scholarly journals GROWTH, PHYSIOLOGY AND YIELD RESPONSES OF FOUR ROCK MELON (CUCUMIS MELO VAR. CANTALOUPENSIS) CULTIVARS IN ELEVATED TEMPERATURE

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Rathnayake Mudiyanselage Nilusha Thushari Amarasinghe ◽  
Siti Zaharah Sakimin ◽  
Puteri Edaroyati Megat Wahab ◽  
ShairulIzan Ramlee ◽  
Juju Nakasha Jaafar
Keyword(s):  
High Temperature ◽  
Leaf Area ◽  
Temperature Stress ◽  
Extreme Temperature ◽  
Carbon Dioxide Concentration ◽  
High Temperature Stress ◽  
Relative Growth ◽  
Growth Physiology ◽  
Malondialdehyde Content ◽  
Yield Responses

Rock melon is a high value greenhouse crop. Reduction of economical crop yield in high temperature stress due to global warming is an emerging issue with Rock melon. Therefore, this study was conducted for evaluate the growth, physiology and yield of different Rock melon cultivars grown under high temperature stress. Four cultivars of rock melon (Lady-gold, Lady-green, Himalai-99 and Glamour) were evaluated for their physiological behaviors under two temperature (42±3°C and 47 ±3°C) regimes. In four cultivars of rock melon, leaf area, specific leaf area, relative growth rate, chlorophyll content, photosynthesis rate, stomatal conductance, intercellular carbon dioxide concentration, transpiration rate, malondialdehyde content and fruit yield of Rock melon were significantly differ in each temperature regime. Temperature significantly affects the fruit position in main branch. When temperature increases, Rock melon fruits shifts in to upper branches. While Lady-green and Glamour shown similar attributes in extreme temperature, most susceptible cultivar was the Lady-gold and most tolerant cultivar was the Himalai-99.This study identified the issues of extreme temperature related to the economical yield of rock melon cultivars which can be use in future crop modification and breeding.

scholarly journals LC/8YSZ TBCs Thermal Cycling Life and Failure Mechanism under Extreme Temperature Gradients

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1051
Author(s):  
Kun Liu ◽  
Xi Chen ◽  
Kangping Du ◽  
Yu Wang ◽  
Jinguang Du ◽  
...  
Keyword(s):  
High Temperature ◽  
Surface Temperature ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Failure Mechanism ◽  
Extreme Temperature ◽  
Temperature Gradients ◽  
Accelerated Life Test ◽  
Ceramic Layer ◽  
Cycling Life

The purpose of this paper is to study the thermal shock resistance and failure mechanism of La2Ce2O7/8YSZ double-ceramic-layer thermal barrier coatings (LC/8YSZ DCL TBCs) under extreme temperature gradients. At high surface temperatures, thermal shock and infrared temperature measuring modules were used to determine the thermal cycling life and insulation temperature of LC/8YSZ DCL TBCs under extreme temperature gradients by an oxygen–acetylene gas flame testing machine. A viscoelastic model was used to obtain the stress and strain law of solid phase sintering of a coating system using the finite element method. Results and Conclusion: (1) Thermal cycling life was affected by the surface temperature of LC/8YSZ DCL TBCs and decreased sharply with the increase of surface temperature. (2) The LC ceramic surface of the failure coating was sintered, and the higher the temperature, the faster the sintering process. (3) Accelerated life test results showed that high temperature thermal cycling life is not only related to thermal fatigue of ceramic layer, but is also related to the sintering degree of the coating. (4) Although the high temperature thermal stress had great influence on the coating, great sintering stress was produced with sintering of the LC ceramic layer, which is the main cause of LC/8YSZ DCL TBC failure. The above results indicate that for new TBC ceramic materials, especially those for engines above class F, their sinterability should be fully considered. Sintering affects the thermal shock properties at high temperature. Our research results can provide reference for material selection and high temperature performance research.

Microstructure Analysis of Melt-Spun Al3Ti Intermetallics by XRD and EXAFS

1996 ◽  
Vol 460 ◽  
Author(s):  
Jinmin Chen ◽  
W. E. Frazier ◽  
E. V. Barrera
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Melt Spinning ◽  
Composition Range ◽  
Processing Parameters ◽  
Wheel Speed ◽  
Annealing Temperatures ◽  
Melt Spun ◽  
Temperature Heat ◽  
Spinning Process

ABSTRACTIn an effort to expand the composition range over which Al3Ti is stable, various amounts of niobium were substituted for titanium and processed by melt-spinning. Several samples were annealed both at 600°C and 1000°C for 24 hours. The effects of processing parameters such as wheel speed, the amount of niobium, and annealing temperatures on the structure were investigated by XRD and EXAFS. XRD showed that for all the samples the only structure present was DO22-The DO22 structure was stable even after the high temperature heat treatments. By means of EXAFS, niobium atoms were observed to occupy titanium sites in the DO22 structure. Furthermore, in the unannealed samples, increasing wheel speed of the melt spinning process or the niobium concentration tended to distort the crystal structure. It was observed that Ti EXAFS had different results from the Nb EXAFS beyond their occupying similar sites, which suggested there may exist some composition zones, i.e. rich Nb zone or rich Ti zones, although the structures present were still DO22. The samples were found to experience different distortions as a function of annealing temperatures.

Novel Elastomer Materials for Extreme Temperature Operation in Subsea Thermal Insulation Applications at Unlimited Water Depth

2021 ◽  
Author(s):  
Adam Jackson ◽  
Rodrigo Diaz ◽  
Heidi Svalund ◽  
Raymond Hansen ◽  
Grethe Hartviksen
Keyword(s):  
High Temperature ◽  
Thermal Insulation ◽  
Water Depth ◽  
Extreme Temperature ◽  
Base Material ◽  
Development Project ◽  
Pressure Vessels ◽  
Hand Tools ◽  
Gentle Pressure ◽  
Cost Efficient

Abstract Rubber based systems have been used in subsea thermal insulation for many years and have proven themselves to be reliable and cost efficient. Formulations have been changed over the years, pressing the maximum usage temperature upwards and into the realm of 160 to180°C in a hot-wet environment. Until recently there was a need for high temperature along with pressure vessels (autoclaves) for vulcanisation. This has limited the widespread use of such systems. Recent changes have eliminated the need for autoclaves, however the high temperature vulcanisation hasstill been required. A novel formulation has been developed to address these shortcomings, so that this class of materials could have wider use. This new material employs freely available materials in a unique blend. The material contains no hydrolysable groups and can operate from −40°C to 180°C continuously in air and in a hot-wet environment and retains its resilience and flexibility; and thus opening for use in both high and low temperature systems. The formulation does not include the use of hollow glass microspheres and is, correspondingly, without water depth limitations. A new, highly reliable vulcanisation chemistry allows for a stable latency time for application, with vulcanisation temperatures reduced to 50°C. This allows for rapid hand application and simultaneous vulcanisation on subsea trees, valves, manifolds, etc. The material is self-agglomerating, merging under gentle pressure, and can be applied at high thickness. As the base material has an intrinsically low thermal conductivity, glass-based fillers are not needed. The material adheres well to painted or primed surfaces and to many other materials typically used in the offshore thermal insulation industry. The 2-component material is conveniently combined on site, reducing the need for refrigeration during transport and easing mobilisation logistics and is applied using simple hand tools. Extruded profiles can be used directly on complex structures or combined into sheets for ease of application on more regular shapes in order to optimise application rates. Moulds are not required for application, reducing engineering and fabrication cost, while also shortening mobilisation time. The system has been extensively qualified according to ISO 12736 for continuous use at 180°C. This paper will detail important aspects of the development project along with the results of the qualification testing.

Creation of an ARM® Cortex®-M0 microcontroller for high temperature embedded systems

2017 ◽  
Vol 2017 (HiTEN) ◽  
pp. 000031-000035 ◽  
Author(s):  
R. Bannatyne ◽  
D. Gifford ◽  
K. Klein ◽  
K. McCarville ◽  
C. Merritt ◽  
...  
Keyword(s):  
High Temperature ◽  
Embedded Systems ◽  
Extreme Temperature ◽  
Processing Technique ◽  
Temperature Cycling ◽  
Electronic Systems ◽  
Challenging Environment ◽  
Silicon Device ◽  
Device Operation ◽  
Latch Up

Abstract This paper will describe the development and testing of a new ARM© Cortex©-M based microcontroller for high temperature electronic systems. High temperature and electrical overstresses can cause latch-up in CMOS devices that will interfere with normal device operation or destroy the device. For reliable operation in the downhole drilling environment it was necessary to immunize this device against latch-up using an innovation processing technique. HARDSIL® technology that allows reliable latch-up free operation at extreme temperatures will be described. Details on the qualification and testing of the product to ensure that it meets the challenging environment will also be discussed. This includes electrical testing and temperature cycling testing to ensure that the different package options for the silicon device are mechanically sound in a high temperature environment that exposes the silicon and packaging materials to thermal cycling. The ecosystem for the microcontroller will also be discussed – hardware and software development tools are required to optimize the use of the device in extreme temperature embedded systems. An ecosystem of components is also required to operate with the microcontroller in the high temperature harsh environment.

Low Temperature Co-fired Ceramics Processing Parameters Governing the Performance of Miniaturized Force Sensors

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000411-000416
Author(s):  
Michael Weilguni ◽  
Walter Smetana ◽  
Goran Radosavljevic ◽  
Johann Nicolics ◽  
Werner Goebl ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Processing Parameters ◽  
Gauge Factor ◽  
Force Sensors ◽  
Stabilized Zirconia ◽  
Temperature Coefficient Of Resistance ◽  
Microscope Images ◽  
Resistive Thick Film

For the development of miniaturized force sensors, built up in ceramics technology with piezo-resistive principle, the compatibility of the piezo-resistive thick-film paste with the substrate and termination paste has to be verified. This paper deals with the compatibility of the ESL 3414-A piezo-resistive paste on HTCC (high temperature co-fired ceramics) substrates (alumina as reference and the partially stabilized zirconia tape ESL 42013-A) as well as on LTCC (low temperature co-fired ceramics) substrates (Heraeus AHT01-005, AHT08-047, CT707; and CeramTec GC) under different manufacturing conditions. The sheet resistance at room temperature, the longitudinal gauge factor at room temperature and the temperature coefficient of resistance have been measured. The results are compared with microscope images showing cracks in distinct cases. Finally, the compatibility and thus applicability of the ESL 3414-A on the investigated substrates is evaluated.

The Effect of Various UHT Processing Parameters and Storage Conditions on the Saturated Aldehydes In Half-and-Half Cream

1991 ◽  
Vol 54 (2) ◽  
pp. 109-112 ◽  
Author(s):  
R.K. HUTCHENS ◽  
A.P. HANSEN
Keyword(s):  
Gas Chromatography ◽  
High Temperature ◽  
Column Chromatography ◽  
Steam Injection ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Tetra Pak ◽  
And Storage ◽  
Ultra High Temperature

Raw cream was standardized to 10% fat and processed by ultra-high-temperature (UHT) steam injection at 149°C for 20 s, 149°C for 3.4 s, 138°C for 20 s, and 143°C for 7 s, then aseptically packaged by a Tetra Pak AB3-250 filler. Packages were stored for 12 months at 24°C and analyzed at 0, 1, 3, 6, and 12 months. Fat-soluble carbonyls were extracted from the UHT cream with carbonyl-free hexanes and converted to their 2,4-dinitrophenyl-hydrazone derivatives. Alkanal hydrazones were separated by column chromatography into pure fractions. Spectrophotometry and gas chromatography were used to identify the alkanals. Butanal, hexanal, heptanal, nonanal, and decanal were identified and found to decrease in concentration during storage.

Sign in / Sign up

Export Citation Format

Share Document