Phase controlled synthesis of transition metal carbide nanocrystals by ultrafast flash Joule heating

Nanoscale carbides enhance ultra-strong ceramics and show activity as high-performance catalysts. Traditional lengthy carburization methods for carbide syntheses usually result in coked surface, large particle size, and uncontrolled phase. Here, a flash Joule heating process is developed for ultrafast synthesis of carbide nanocrystals within 1 s. Various interstitial transition metal carbides (TiC, ZrC, HfC, VC, NbC, TaC, Cr2C3, MoC, and W2C) and covalent carbides (B4C and SiC) are produced using low-cost precursors. By controlling pulse voltages, phase-pure molybdenum carbides including β-Mo2C and metastable α-MoC1-x and η-MoC1-x are selectively synthesized, demonstrating the excellent phase engineering ability of the flash Joule heating by broadly tunable energy input that can exceed 3000 K coupled with kinetically controlled ultrafast cooling (>104 K s−1). Theoretical calculation reveals carbon vacancies as the driving factor for topotactic transition of carbide phases. The phase-dependent hydrogen evolution capability of molybdenum carbides is investigated with β-Mo2C showing the best performance.

Modelling the Heating Process in the Transient and Steady State of an In Situ Tape-Laying Machine Head

As the use of composite materials increases, the search for suitable automated processes gains relevance for guaranteeing production quality by ensuring the uniformity of the process, minimizing the amount of scrap generated, and reducing the time and energy consumption. Limitations on production by traditional means such as hand lay-up, vacuum bagging, and in-autoclave methods tend not to be as efficient when the size and shape complexity of the part being produced increases, motivating the search for alternative processes such as automated tape laying (ATL). This work aims to describe the process of modelling and simulating a composite ATL with in situ consolidation by characterizing the machine elements and using the finite differences method in conjunction with energy balances in order to create a digital twin of the process for further control design. The modelling approach implemented is able to follow the process dynamics when changes are made to the heating element and to predict the composite material temperature response, making it suitable for use as a digital twin of a production process using an ATL machine.

Temperature and curvature-dependent thermal interface conductance between nanoscale-gold and water from molecular simulation

Plasmonic gold nanoparticles (AuNPs) can convert laser irradiation into thermal energy and act as nano heaters in avariety of applications. Although the AuNP-water interface is an essential part of the plasmonic heating process,there is a lack of mechanistic understanding of how interface curvature and the heating itself impact interfacial heattransfer. Here, we report atomistic molecular dynamics simulations that investigate heat transfer through nanoscalegold-water interfaces. We confirmed that interfacial heat transfer is an important part of AuNP heat dissipation inAuNPs with diameter less than 100 nm, particularly for small particles with diameter≤10 nm. To account forvariations in the gold-water interaction strength reported in the literature, and to implicitly account for differentsurface functionalizations, we modeled a moderate and a poor AuNP-water wetting scenario. We found that thethermal interface conductance increases linearly with interface curvature regardless of the gold wettability, while itincreases non-linearly, or remains constant, with the applied heat flux under different wetting conditions. Our analysissuggests the curvature dependence of the interface conductance is due to the changes in interfacial water adsorption,while the temperature dependence is caused by heat-induced shifts in the distribution of water vibrational states.Our study advances the current understanding of interface thermal conductance for a broad range of applications.

An Effect of a Carbon-Containing Additive in the Structure of a Friction Material on Temperature of the Wet Clutch Disc

This paper consists of two parts. The first one contains a description and methodology of the composite material used as friction material in clutches. Four variants of such material, differing in the type of carbon additive (the elemental graphite, pencil graphite and foundry coke powder of various fractions) were considered. Thermal conductivity, thermal diffusivity as well as the specific heat all materials were determined experimentally. On the inertial IM-58 stand, a simulation of the braking process of the friction pair consisting of a steel disc with friction material and a counterpart in the form of a homogeneous steel disc was carried out. On this basis, averaged coefficients of friction, unchanging in the entire sliding process, were found for the four friction pairs. The experimental data obtained in the first stage were used in the second stage to develop two (2D and 3D) numerical models of the friction heating process of the friction pairs under consideration. For four variants of the friction material, a comparative spatial-temporal temperature analysis was performed using both models. It was found that a simplified axisymmetric (2D) model can be used to estimate the maximum temperature with high accuracy. The lowest maximum temperature (115.6 °C) obtained for the same total friction work was achieved on the friction surface of the material with the addition of GP-1.

A Fast Approach to Obtain Layered Transition-Metal Cathode Material for Rechargeable Batteries

Li-ion batteries as a support for future transportation have the advantages of high storage capacity, a long life cycle, and the fact that they are less dangerous than current battery materials. Li-ion battery components, especially the cathode, are the intercalation places for lithium, which plays an important role in battery performance. This study aims to obtain the LiNixMnyCozO2 (NMC) cathode material using a simple flash coprecipitation method. As precipitation agents and pH regulators, oxalic acid and ammonia are widely available and inexpensive. The composition of the NMC mole ratio was varied, with values of 333, 424, 442, 523, 532, 622, and 811. As a comprehensive study of NMC, lithium transition-metal oxide (LMO, LCO, and LNO) is also provided. The crystal structure, functional groups, morphology, elemental composition and material behavior of the particles were all investigated during the heating process. The galvanostatic charge–discharge analysis was tested with cylindrical cells and using mesocarbon microbeads/graphite as the anode. Cells were tested at 2.7–4.25 V at 0.5 C. Based on the analysis results, NMC with a mole ratio of 622 showed the best characteristicd and electrochemical performance. After 100 cycles, the discharged capacity reaches 153.60 mAh/g with 70.9% capacity retention.

Kualitas Produk Peralatan Pertanian Hasil Tempa Panas Pengrajin Pande Besi Melalui Penerapan Desain Dapur Perlakuan Panas Model Tutup

The problems encountered by artisan blacksmiths based on the field study results: unable to detect incineration temperature of wood charcoal in the crucibles, crusts occurrence on the metal surface of scrap component of spring leaf SUP 9 after heating process in the exposed model heating treatment. The solutions taken were by transforming the kitchen design, from exposed model heating treatment to closeted model heating treatment, which aimed to avoid oxidation on the incinerated metal, thus crusts do not occur on its surface. The kitchen wall of closeted model heating treatment was made from fireproof bricks, held heat resistance, and carried a stable thermal conductivity out of wood charcoal incineration. A digital thermocouple was installed in the closeted model heating treatment kitchen to accurately measure the temperature of wood charcoal incineration results. The closeted heating model treatment kitchen was designed portable. The solution methods applied field study and descriptive analysis. The study generated a result of sturdiness value with 18.8 HRC average for hoe products was below the standard of sturdiness value according to SNI 02-0331-1989 and generated a result of kitchen wall of closeted model heating treatment made from red bricks with cement as the fastener could not stand the heat. The conclusion for the application of kitchen design of closeted model heating treatment were the sturdity values achieved 58 HRC with SAE 900 C as the cooling lube and the wear rate achieved 0.000165605 gram/m. This meant the wear resistance property was low which met the standard according to SNI 02-0331-1989. Abstrak Permasalahan pengrajin pande besi sesuai hasil studi lapangan: temperatur pembakaran arang kayu di dalam kowi tidak dapat dideteksi, permukaan logam bekas komponen pegas daun SUP 9 timbul kerak setelah proses pemanasan di dalam dapur perlakuan panas model buka. Metode pemecahannya melakukan inovasi pada desain dapur perlakuan panas model buka dirubah menjadi desain dapur perlakuan panas model tutup yang bertujuan: material logam yang dipanasi tidak teroksidasi, sehingga permukaan logam tidak timbul kerak, dinding dapur perlakuan panas model tutup terbuat dari bata tahan api, mempunyai sifat tahan panas serta konduktivitas panas hasil pembakaran arang kayu stabil, dapur perlakuan panas model tutup dipasang termokopel digital agar temperatur hasil pembakaran arang kayu terukur dan akurat, dan dapur perlakuan panas model tutup dirancang dapat dipindah-pindah tempat. Metode pemecahannya menggunakan metode studi lapangan dan metode analisis deskriptif. Hasil-hasil temuan yang diperoleh angka kekerasan produk cangkul rata-rata 18,8 HRC masih di bawah angka kekerasan cangkul menurut SNI 02-0331-1989, dinding dapur perlakuan panas model buka terbuat bata merah dengan pengikat semen tidak tahan panas. Simpulan dengan penerapan desain dapur perlakuan panas model tutup, angka kekerasan mencapai 58 HRC dengan media pendinginan oli SAE 90 dan laju keausan 0.000165605 gram/m memenuhi SNI 02-0331-1989, sehingga sifat ketahanan ausnya rendah.

Analysis of vitamin C in probiotic yoghurt with the addition of podang urang mango (Mangifera indica L.)

Yoghurt is a functional drink that is beneficial to health. However, nutritional losses, e.g. vitamin C, occurs during the thermal process. Therefore, vitamin C supplementation is needed to replace the lost amount during processing by adding the extract of podang urang mango (Mangifera indica L.). The yoghurt was made by adding 3% (v/v) of starter culture (Lactobacillus delbrueckii subsp bulgaricus RRAM-01 and Streptococcus salivarus subsp thermophillus RRAM-01) and mango extract at 0%, 2%, 4%, 6%, 8% and 10% (v/v) in four replications. The determination of vitamin C content was performed using titration method. The results showed that heating process at 85-90 °C in 35 minutes lowered the amount of vitamin C in the final product. However, the addition of podang urang mango extract at 6%, 8% and 10% could increase the amount of vitamin C.

Application of Virtualization for Process Control Experiments

The virtualization of the Festo process control teaching platform and the implementation process of extending it with real industry applications are introduced. Taking the heating process of the water tank as an example, the model extraction method of the real object is analyzed in detail, and the model identification problem of the low-order linear control object is solved. Through the introduction of the creation process of the object model on the virtual platform, a feasible way is pointed out for similar applications. On this basis, it is proposed to integrate the teaching platform with the specific industrial industry in the virtualized environment, broaden the breadth of process control teaching, and point out new ideas for building a teaching profession with industry support.