Devices thermal treatment

Industrial furnaces are enclosed units that are integral parts of a manufacturing process and use thermal treatment to recover materials or energy from hazardous waste. These units may use hazardous waste as a fuel to heat raw materials to make a commodity (e.g., a cement kiln making cement) or the unit may recover materials from the actual hazardous waste (e.g., a lead smelter recovering lead values). The following 12 devices meet the definition of an industrial furnace12 ... 

An industrial furnace is a unit that is an integral part of a manufacturing process and uses thermal treatment to recover materials or energy. The 12 devices that are considered to be industrial furnaces can be found in Table 23.1. An example of such industrial furnaces23 is shown in Figure 23.2. 

Laboratory furnaces. Several types of furnaces are used in the laboratory these are often available as commercial rigs, generally equipped with more or less sophisticated temperature measurement and control devices. As an alternative, a lab-made or commercial furnace and its temperature measuring devices may be connected to a multi-channel data acquisition/actuator/switch unit, to be programmed by a personal computer, in order to plan and carry out thermal treatments, to collect and retrieve measured thermal data, etc. 

Polymer nanotubes composites are now extensively studied. Indeed, one may associate the properties of the polymer with those of nanotubes. This is the case of the mechanical reinforcement of standard polymer for example, but also one can take advantage of the specific electronic properties of the nanotubes. Therefore, we prepared composites with either saturated polymers like polymethylmethacrylate and MWNTs [27]. The electrical conductivity of these compounds as a function of the nanotube content exhibits for example a very low percolation threshold, (a few % in mass) and therefore they can be used as conducting and transparent layers in electronic devices such as Light Emitting Diodes (LEDs). Another type of composite that we have studied is based on the use of a conjugated polymer, polyphenylene-vinylene (PPV) known for its photoluminescence properties and SWNTs. We prepared this composite by mixing SWNTs to the precursor polymer of PPV. The conversion into PPV was subsequently performed by a thermal treatment at 300°C under dynamical vacuum [28],... 

Alumina support modified with Ni is ready for palladium deposition which can be carried out in the same device. Pd (Pd alloy) deposition should be followed by additional thermal treatment for the complete inter phase diffusion of Ni and Pd. 

A systematic investigation of intrinsic chemical stability was carried out on devices specially designed for high power applications [7]. For this purpose, accelerated ageing test procedures were developed for nc-DSCs and it turned out that, to first order, a separation can be made between the effects of visible light soaking, UV illumination and thermal treatment on long term stability. 

The thermal treatment device for pyrolysis should be properly designed and operated in order to be more economical in terms of a cost-effective and energy-efficient operation. The primary driving force for this process is the intraparticle heat condnction. The principles of a pyrolyzer design shonld take the heat transfer and contact mode into acconnt. Different reactors are nsed to carry ont pyrolysis of the waste plastics. Among them, three... 

Recently in the field of physics of semiconductors and materials science a great attention has been paid to formation and optical properties of semiconductor nanocrystals (quantum dots, QDs) dispersed in inorganic matrixes. An interest to glassy materials with QDs is associated with their unique physical properties and possibility to create elements of optoelectronic devices. Phase separation processes followed by crystallization are the basic in production of such materials. They result in formation of semiconductor nanocrystals stabilized within a glass matrix. The materials are advanced for various applications because of optical and thermal stability and possibility to control optical features through the technology of glass preparation and post-synthesis thermal treatment. 

Fig. 1. (a) Architecture of the devices showing the fabrication of the device with the simultaneous electrical and thermal treatments, (b) Schematic energy levels of the device after the simultaneous treatments. 

The organic salt of tetrabutylammonium tetrafluoroborate (BujNBF ) was further dissolved into the basic organic solution at an appropriate concentration. The thickness of the spin-coated organic layer was about 80 nm. Then, an A1 cathode layer (100 nm) was formed on the top of the organic layers via thermal deposition at a rate of 0.7 nm/ s under a base pressure of 2 x 1Q Torr. In this experiment, phosphorescent OLEDs were fabricated and comprared one with BU4NBF4 (0.0050 wt%) annealed electrically at V = +7 V (forward bias) at T = 65°C the other for reference with BU4NBF4 (0.0050 wt%) annealed electrically at V = +20 V (forward bias) at T = 25°C. It should be noted that, except for the emissive layer, the device structure of the reference device was identical to that of the sample device. The structures of the devices and materials used were identical. The devices were prepared in inert Ar gas environments this preparation included electrical and thermal treatments. 

Fig. 2. Current flows of sample (left) and reference (right) devices with organic salt during electrical and thermal treatments for given temperatures. The inset shows the voltage ptrofile applied to the devices. (Oh et al, 2007)...

Therefore, by applying electric and thermal treatments simultaneously, homogeneous and enhanced EL emission was obtained from the active area of the devices with high reproducibility. Moreover, the efficiency of the devices was also observed to improve. As a result, an ionic f-i-n PHOLED with a peak external quantum efficiency of 8.6 % was achieved in the sample device. On the basis of these results, it is demonstrated that simultaneous annealing can lead to more efficient electroluminescence through increased and balanced carrier injection. This improvement can be attributed to the excellent balancing of holes and electrons. 

Analogous to the electrical conditioning, the OFET characteristics can be improved by a thermal treatment prior to the deposition of the source-drain metallisation. The improvement in the device performance can be seen in the insets of Figures 24.8 and 24.9, showing the OFET parameters, measured at RT, for devices exposed to different annealing temperatures for / = 1 h. The examined devices comprised a 8 A Ca passivation layer. It can be noted that an annealing temperature of 160 °C resulted in a device performance, comparable to the one obtained by the electrical cyclic conditioning. 

Even though the origin of the improvement in OFET device characteristic upon a thermal treatment seems unveiled it is still unclear what causes the enhancement due to electrical cyclic stress. Flowever, additional experiments have shown that a electrical cyclic conditioning of annealed transistors does not yield a significant additional improvement in the device performance. We therefore suggest that the observed OFET improvement for both device treatments, have the same consequence. This implies that the electrical cyclic conditioning also leads to a promoted oxidation of the metallic fraction in the Ca passivation, as discussed for the substrate aimealing. 

Thermal treatment may use either direct or indirect heating. Direct heating uses direct contact with combustion gas or heat carrier gas to heat the contaminated media. Indirect heating inputs heat by contacting the debris with a heated wall, screw impeller, or other device. The device is in turn heated by an external source, such as a heat transfer fluid (e.g., hot oil or hot gas) or a radiant heat source. 

Fig. 6. Furnace used for thermal treatment of samples during SAXS/ WAXS measurements. The device is especially designed for rapid temperature changes (150 ° /min.)...

For use in PV devices, the absorber layer must be uniform laterally on both the micrometer and centimeter length scales with respect to its composition, and vertically on the micrometer length scale with respect to its thickness. Lateral uniformity on the centimeter scale is a prerequisite for fabrication of larger area PV devices, and the vertical thickness needs to be uniform in order to avoid stress in subsequent deposited layers and to avoid pinhole formation. A final criterion to consider is that the absorber layer must adhere well to the substrate so that it can withstand subsequent thermal treatment. 

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