Heating hot plates

Thermal CVD requires high temperature, generally from 800 to 2000°C, which can be generated by resistance heating, high-frequency induction, radiant heating, hot plate heating, or any combination of these. Thermal CVD can be divided into two basic systems known as hot-wall reactor and cold-wall reactor (these can be either horizontal or vertical). 

Add about 400 mL of water to a 600-mL beaker. Using a hot plate, heat the water until it boils. CAUTION The hot plate and boiling water can cause burns. 

Set up a boiling-water bath by adding 150 mL of water to a 250-mL beaker. Add a few boiling chips to the water and place the beaker on the hot plate. Heat the water until it starts boiling. 

Place the beaker on a hot plate, heat to 100°C, and let evaporate until a thin film of liquid remains on the bottom. 

The laminate in which the impregnated glass cloths are sandwiched between the PTFE films is then polymerized by adhering onto a hot plate heated at 145°C for 1 min. Thereafter, the PTFE films are peeled off to get a prepreg. Eventually the prepreg is laminated on both sides with a copper foil and a PTFE film having a thickness of 0.05 mm. The laminate is then put into a mold and heat pressed in the mold frame under a press pressure of 4.1 MPa at 200°C for 15 min. 

If you are using a hot plate, heat the beaker with the hydrated copper(II) sulfate until the crystals lose their blue colour. You may need to stir occasionally with the glass rod. 

Transfer the filter paper and precipitate into a tared platinum crucible, char, and ignite at 900° to constant weight. Moisten the residue with a few drops of water, add 15 mL of hydrofluoric acid and 8 drops of sulfuric acid, and heat on a hot plate in a hood until white fumes of sulfur trioxide evolve. Cool add 5 mL of water, 10 mL of hydrofluoric acid, and 3 drops of sulfuric acid and evaporate to dryness on the hot plate. Heat cautiously over an open flame until sulfur trioxide fumes cease to evolve, and ignite at 900° to constant weight. The weight loss after the addition of hydrofluoric acid represents the weight of Si02 in the sample taken. 

Nitroethylene Polymer (NEtPol) [H2C CH.N021x mw[73.05la> N 19.17%, OB to COa-7% wh amorphous solid, mp-did not melt, but de-coffipd slowly at 75°, igniting after 2 hours of heating being heated at 100°, it deflagrated with evoln of a brown sooty smoke when placed on a hot plate heated at 200°, it spontaneously decompd without expln. 

In such an application, the initial impulse closes the lower set of contacts on the relay, introducing 115 volts of electricity into the hot plate heating element. The plate comes quickly to maximum heat, igniting the flammable material,... 

Since the most important industrial CVD-W reactors essentially use hot plate heating we will direct most of our attention to this type of wafer heating. 

Figure 7.1. Schematic representation of the main heat transfer routes in a cold wall reactor with hot plate heating (see text for details).

In the case of direct wafer heating by lamp heating there is a difference in the way heat arrives at the back side of the wafer. Now the main transfer route of heat to the wafer is that by radiation which is independent of the pressure. This implies that the wafer temperature can depend much more on the process pressure since pressure affects only the heat loss from the front side of the wafer. With the hot plate heating both the incoming and the outgoing fluxes are influenced by pressure which leads partly to cancellation. In addition the determination of the wafer temperature is even more complicated than in case of hot plate heating because the wafer has to be monitored directly (thermocouple against wafer or pyrometer). 

The success of the escape of naive rats from the hot plate depends primarily on the efficiency of their mesencephalic catecholaminergic machinery. This was shown in rats pretreated for 4 weeks, once daily, with 0.1 mg/kg reserpine. None of a group of ten reserpine-treated rats escaped from a hot plate heated to 55 °C they all died. However, seven out of ten reserpine-treated rats safely escaped when the temperature of the hot plate was raised to 60 °C (see Table 19 in Knoll 1969). 

The results shown in Table 3.7 are especially apt in support of this conclusion. There are innate differences in the efficiency of the mesencephalic catecholaminergic system. For the brain of animals (nos.) 1, 2, 4, 5, and 6 the hot plate heated to 50 °C was already an adequate stimulus to enhance the excitability of the cortical neurons for escape and to survive the tribulation without perceivable consequences. Animals 3 and 7 escaped, but fell ill thereafter. Animals 8, 9, and 10 were unable to cope with the situation and died. 

Hot plates, heating mantles, and steam baths are commonly used as heaters. Burners are not used unless nonflammable materials are involved or unless rapid heating is required. Hot plates. Figure 3-16, are relatively inexpensive and simple to operate, but they do not always provide even heat over the entire bottom of a round-bottom flask. 

Perhaps the most common types of electrical equipment found in a laboratory are the devices used to supply the heat needed to effect a reaction or a separation. These include ovens, hot plates, heating mantles and tapes, oil baths, salt baths, sand baths, air baths, hot-tube furnaces, hot-air guns, and microwave ovens. The use of steam-heated devices rather than electrically heated devices is generally preferred whenever temperatures of 100 °C or less are required. Because they do not present shock or spark risks, they can be left unattended with assurance that their temperature will never exceed 100 °C. 

Place 0.375 g ytterbium (III) trifluoromethanesulfonate hydrate catalyst (ytterbium triflate) into a 25-mL round-bottom flask. Add 10 mL of 1,2-dichloroethane solvent followed by 0.400 mL of concentrated nitric acid (automatic pipette). Add two boiling stones to the flask. To fhis solution, weigh out and add approximately 6 millimoles of the aromatic substrate. Connect the round-bottom flask to a reflux condenser and clamp it into place on a ring stand. Use a very slow flow of water through the condenser. With a hot plate, heat the mixture to reflux for 1 hour. 

Figure 3.13 Optical microscopy image of wax water Si02 capsules obtained with an increased TEOS concentration (5 wt% with respect to the PDMS oily phase), (a-f) Sequenced images showing the wax release scenario when the temperature is increased to 44 °C by means of a Mettler hot plate (heating...

FIGURE 10.1 Comparison of methods of heating (a) Heat from the hot-plates heats the glass base of the beaker and is transferred by the convection, (b) The solution heats slowly as microwaves pass through the vessel walls directly into the polar liquid. 

To make a the photo-tailorable SMP (PT-SMP), a commercially available UV curable polymer (Norland Optical Adhesive (NOA) 63, Norland Products, Inc.) was cured using a high intensity ultraviolet lamp (365 nm, Spectronics Corporation, Model SB-1 OOP) isolated with a box for safety. To prepare smooth PT-SMP films, two quartz plates (2 cm x 3 cm) were employed to form the top and bottom mold surfaces with a spacer (1.5 mm thickness) being placed between the plates. A distance separating the UV lamp and the mold was set at 5 cm. After curing for prescribed periods of time, crosslinked PT-SMP samples were removed from the quartz substrate by placement on a hot plate heated to 70 °C, a temperature allowing convenient pealing away of the film from the mold. 

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