Thermo-mechanical Processing for In-situ Cu-based Composites

In-situ Cu-based composites have been investigated extensively over the past decades because of their good conductivity and high strength. The preparation technologies of in-situ Cu-based composites mainly include casting of Cu alloys, initial heat treatment, hot deformation, cold deformation, intermediate and final heat treatment. This paper primarily researched the effect of thermo-mechanical processing such as initial heat treatment, hot deformation, cold deformation, intermediate and final heat treatments on the property and microstructure of in-situ Cu-based composites, analyzed the main role and mechanism of each thermo-mechanical processing, summarized the related research work and achievements, and prospected the future main research directions of the thermo-mechanical processing for in-situ Cu-based composites.

Influence of Pre-Aging on the Artificial Aging Behavior of a 6056 Aluminum Alloy after Conventional Extrusion

In the present study, the influence of the initial heat-treatment conditions on the artificial aging behavior after conventional linear extrusion at room temperature was investigated for the precipitation hardening of a 6056 aluminum alloy. A solution-annealed condition was systematically compared to naturally-aged and pre-aged conditions. Differential scanning calorimetry was used for analyzing the precipitation sequence and its dependence on the initial heat treatment. The natural aging behavior prior to extrusion and the artificial aging behavior after extrusion were determined by microhardness measurements as a function of the aging time. Furthermore, the microstructure, dependent on the induced strain, was investigated using optical microscopy and transmission electron microscopy. As a result of pre-aging, following a solid-solution treatment, the formation of stable room-temperature clusters was suppressed and natural aging was inhibited. The artificial aging response after extrusion was significantly enhanced by pre-aging, and the achieved hardness and strength were significantly higher when compared with the equally processed solution-annealed or naturally-aged conditions.

Effect of Premixed n-Butanol Ratio on the Initial Stage of Combustion in a Light-Duty Butanol/Diesel Dual-Fuel Engine

The impact of premixed n-butanol mixture on the heat release rate was investigated based on a modified light-duty diesel engine. The results show that reactivity stratification is formed in the cylinder through n-butanol port fuel injection (PFI) and diesel direct injection (DI). The initial heat release rate of the diesel/butanol dual-fuel combustion is restrained due to the low ignitability of butanol and the high volatility. Because of the auto-ignition of diesel, premixed n-butanol undergoes a high-temperature reaction, which has an active influence on the heat releasing of diesel/butanol dual-fuel combustion. With the increase of the amount of premixed n-butanol injected, the heat release rate in the initial combustion period has a critical value. When the n-butanol injection quantity is less than 13 mg/cycle, the initial heat release rate of dual-fuel combustion is lower than the pure diesel combustion because the lean premixed n-butanol/air mixture limits the flame propagation. When the fuel injection rate of n-butanol is higher than 13 mg/cycle, the heat release rate is accelerated, leading to obvious flame propagation.

Evaluation of the Sorption Phenomena Mechanism of Polyacrylonitrile Fibres for Selected Dyes in the Aspect of Structural Changes Resulting from Thermal Stabilisation Processes

The aim of the research was to analyse the influence of the initial heat treatment of polyacrylonitrile fibres on their sorption properties in relation to selected basic and disperse dyes, in order to select the dyeing variants most beneficial from the point of view of increasing the sorption capacity of commonly used dyes and improving the dyeing process. Research was carried out on a fibre produced on an industrial scale, using dyes of basic application importance, which differ in the diffusion properties of the molecules and the mechanism of binding with the fibre material. Thermal treatment of the fibre was carried out in various media (air, water, steam), with various variants of the temperature and its duration, i.e. under the conditions commonly used in fibre preprocessing processes and their “improvement”. During the research, several different measurement methods were used to assess changes in the molecular and supramolecular structure of the fibre material: the infrared absorption spectroscopy method, the critical fibre dissolution measurement method, the densitometric method, and the interferential polarisation microscopy method. Fibre sorption changes resulting from the modification of the structure of the fibre under the influence of thermal treatment were analysed from the point of view of improving the efficiency of dye use and shortening the dyeing time based on commonly accepted values of the sorption index Cb and kinetic sorption index: t0.5 for basic dyes and t0.7 for disperse dyes.

Pengaruh Kolektor Pelat Gelombang Dengan Dua Kaca Penutup Terhadap Penambahan Panas Untuk Meningkatkan Kinerja Solar Water Heater

The worked principle of solar collector wave absorber plate was to transfer solar radiation to the worked fluid. The solar radiation that falls on the first glass was partially reflected, then on the second glass partially absorbed by the absorbent plate. The heat absorbed by the absorbent plate will be used to heat the worked fluid (water) between the absorbent plate and the storage plate. The purpose of this research was to design and make solar collector used wave plate with two cover glass. The addition of incomed water heat used temperatures of 30 ° C, 40 ° C, 50 ° C. The method used was used an expriment by analyzed the effect of initial heat addition on efficiency. From the results of test data obtained collector performance of solar water heater the greater the addition of heat used then the smaller the efficiency. Each of the average heat additions efficiency at 30 ° C was 19.66%, the temperature of 40 ° C was 17.75%, and the temperature of 50 ° C was 12.23%.

The evolution of laminar thermals

We consider the life cycle of an axisymmetric laminar thermal starting from the initial condition of a Gaussian buoyant blob. We find that, as time progresses, the thermal transitions through a number of distinct stages, undergoing several morphological changes before ending up as a vortex ring. Whilst each stage is interesting in its own right, one objective of this study is to set out a consistent mathematical framework under which the entire life cycle can be studied. This allows examination of the transition between the different stages, as well as shedding light on some unsolved questions from previous works. We find that the early stages of formation are key in determining the properties of the final buoyant vortex ring and that, since they occur on a time scale where viscosity has little effect, the final properties of the ring display an independence above a critical Reynolds number. We also find that rings consistently contain the same proportion of the initial heat and have a consistent vorticity flux. By considering the effect of Prandtl number, we show that thermal diffusion can have a significant impact on development, smoothing out the temperature field and inhibiting the generation of vorticity. Finally, by considering the wake left behind as well as the vortex ring that is generated, we observe that the wake can itself roll up to form a second mushroom cap and subsequently a secondary vortex ring that follows the first.

NEW DIRECTION IN LIQUID QUENCHING MEDIA DEVELOPMENT

It is shown that in contrast to well known surface active additives (SAA), affecting physical properties of a liquid, the elimination of film boiling during quenching is achieved by creation of the thin polymeric layer on the surface of hardened metal. It is performed by using special polymers of optimal concentration in water. The obtained insulating polymeric layer decreases initial heat flux density below its critical value and by this way eliminates completely the film boiling without affecting clearly the physical properties of a liquid. Based on this fact and on the principle of decreasing distortion, quench crack formation, and increasing strength of material during intensive quenching, it is proposed to use low concentration of special polymers instead of their high concentration in water. All of this results in significant strengthening of metal, saves costly materials, and increases service life of hardened products.

Pengaruh Kolektor Pelat Gelombang Dengan Dua Kaca Penutup Terhadap Penambahan Panas Untuk Meningkatkan Kinerja Solar Water Heater

The worked principle of solar collector wave absorber plate was to transfer solar radiation to the worked fluid. The solar radiation that falls on the first glass was partially reflected, then on the second glass partially absorbed by the absorbent plate. The heat absorbed by the absorbent plate will be used to heat the worked fluid (water) between the absorbent plate and the storage plate. The purpose of this research was to design and make solar collector used wave plate with two cover glass. The addition of incomed water heat used temperatures of 30 ° C, 40 ° C, 50 ° C. The method used was used an expriment by analyzed the effect of initial heat addition on efficiency. From the results of test data obtained collector performance of solar water heater the greater the addition of heat used then the smaller the efficiency. Each of the average heat additions efficiency at 30 ° C was 19.66%, the temperature of 40 ° C was 17.75%, and the temperature of 50 ° C was 12.23%.Keywords : wave absorbent plate, added heat, solar water heaterAnonim, 2017: wibe site: unmermadiun.ac.id, tanggal 26 Agustus 2017.Anonim. Bab II Landasan Teori Prinsip Kerja Kolektor suryaPelatPenyerap. 809b5f3ff5dc603fbc474afe006faef2,Tanggal 16 Mei 2017.Anggraini, Ekadewi Handoyo, 2002: Jurnal Teknik Mesin Universitas PETRA, Surabaya.Arismunandar, W. 1995. Teknologi Rekayasa Surya. edisi pertama. PT Pradnya Paramita. Jakarta.Burhanuddin, A. 2006. Karakteristik kolektor surya pelat datar dengan variasi jarak kaca penutup dan sudut kemiringan kolektor. Skripsi. Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Sebelas Maret, Surakarta.Beizer, 1981, Konsep Fisika Modern. Jilid 3. Terjemahan The Houw Liong Ph.D, Penerbit Erlangga, Jakarta.Culp, 1991, Prinsip-prinsip Konversi Energi, Penerbit Erlangga, Jakarta.Duffie, dan Beckman. , 1991: Solar Engineering of Thermal Processes, John Willey and Sons Inc, Wisconsin.Giancoli, 1998: Fisika edisi kelima (Terjemahan Yuhilza Hanum), Erlangga, Jakarta.Jasjfi, 1995: Perpindahan kalor, Erlangga, Jakarta.Lunde, 1980, jbptitbpp-gdl-rahadianef-30837—2008ta-2.pdf, Bab II, Teori dasar 8.Maftukhil Murot, dkk., 2016. Pengaruh Penambahan Tekanan Diatas Pelat Penyerap Terhadap Kinerja Solar Water Heater Sederhana, Widya Teknika, Vol. 24, N0. 2: 20-32.Mustofa, 2008, Studi Eksperimen Pengaruh pelat penyerap ganda model gelombang dengan penambahan reflektor terhadap kinerja Solar Water Heater sederhana, Dosen Teknik Mesin, Universitas Merdeka Madiun.Mustofa, Ismail N. R., 2013, International Jurnal of Research in Engineering and Technologi, volume.02, Issue.09, September 2013.Prijono, 1986, Prinsip-prinsip Perpindahan Panas, Penerbit Erlangga, Jakarta.Rahadian, 2008 : Jurnal Teknik Mesin Universitas Sumatra Utara.Sijabat, Andri M. 2014. Rancang Bangun dan Analisa Kolektor Surya Tipe Pelat Datar Bersirip Untuk Penghasil Panas Pada Pengering Hasil Pertanian dan Perkebunan. Skripsi. Fakultas Teknik Universitas Sumatra Utara, Medan.Subur Edi S., Irfan Santoso. 2014. Jurnal Teknologi: Perancangan Solar Water Heater Jenis Pelat Datar Temperatur Medium Untuk Aplikasi Penghangat Air Mandi. Volume 7 Nomor 2: 118-127.Tirtoatmodjo, R., Ekadewi, A. H, 1999: Jurnal Teknik Mesin Universitas Kristen Petra