Controlled-temperature furnace

Temperatures above 300 K are sometimes desirable for Fe work, and a controlled-temperature furnace is then required [68, 69]. The sample is frequently sandwiched between thin discs of beryllium, graphite, or aluminium (m.p. 660°C) attached to an electric heating coil in a vacuum. Alternatively [70], the sample can be placed in a furnace with thin entrance and exit windows and containing an atmosphere of hydrogen to prevent oxidation. A vacuum furnace capable of providing temperatures up to 1000°C has been described [71] and temperatures of 1700°C have been reached with a helium-filled oven with beryllium windows [72]. 

In sintering, the green compact is placed on a wide-mesh belt and slowly moves through a controlled atmosphere furnace (Fig. 3). The parts are heated to below the melting point of the base metal, held at the sintering temperature, and cooled. Basically a solid-state process, sintering transforms mechanical bonds, ie, contact points, between the powder particles in the compact into metallurgical bonds which provide the primary functional properties of the part. 

The first thing to note is that the furnace surrounds the sample-holder containing the differential thermocouples. A separate control thermocouple controls the furnace temperature and should be placed as close as possible to the position of the sample holder. Some commercial manufacturers use the Reference leg of the differential thermocouple to control the temperature. However, if you were to build a DTA using the components as shown in 7.1.14,... 

The carbon or silica-loaded nanoparticles were treated in a tube-furnace under controlled temperature and atmosphere. A typical protocol involved shell removal by heating at 300°C under 20% O2/N2 for 1 h and calcination at 400°C under 15% H2/N2 for 2 h. The carbon-loaded Au or AuPt nanoparticles are denoted as Au/C or AuPt/C. The silica-loaded AuPt nanoparticles are denoted as AuPt/Si02. 

The schematic set-up for a thermogravimetric experiment is shown in Figure 16-2. The device is a combination of a sophisticated high temperature furnace (with temperature and gas atmosphere control) and a micro-balance. Since it is meant to... 

In a DSC experiment the difference in energy input to a sample and a reference material is measured while the sample and reference are subjected to a controlled temperature program. DSC requires two cells equipped with thermocouples in addition to a programmable furnace, recorder, and gas controller. Automation is even more extensive than in TA due to the more complicated nature of the instrumentation and calculations. 

Figure 7.2 Inlet temperature control with furnace.

In Chapter 2, we reviewed the concept of carrying out CVD processes at low pressure so that deposition becomes surface controlled. When the only thing controlling the uniformity of deposition is the temperature of the wafer surface, all we have to do is ensure that the wafer is in a uniform temperature furnace. Again, at low pressures, the diffusion coefficient is so large that we can stack wafers up next to each other so 50 to 100 can be placed in a long tubular furnace. 

The amount of water adsorbed after the samples were outgassed was controlled by adjustment of the pressure in one of three ways use of a sensitive Cartesian diver manostat, use of a water source at a controlled temperature, or use of the mixed magnesium perchlorate hydrates mentioned above. The amount of water adsorbed by the sample was measured either by the gain in weight of a companion sample or by interpolation from the isotherm at 23.5° C. The heat of immersion of samples with no water adsorbed was determined with samples sealed off from the vacuum line while they were still in the furnace at 500° C. 

Pyrolysis Furnace The sample should be pyrolyzed in an electric furnace having at least two separate and independently controlled temperature zones, the first being an inlet section that can maintain a temperature sufficient to volatilize all the organic sample. The second zone is a pyrolysis section that can maintain a temperature sufficient to pyrolyze the organic matrix and oxidize all the organically bound sulfur. A third outlet temperature zone is optional. 

The x-ray studies were made with a high-temperature x-ray diffraction camera of Hume-Rothery design. This camera had a 9-cm. diameter and employed the Straumanis film setting. A fine Chromel-Alumel thermocouple within the furnace cavity and adjacent to the sample served to measure and control temperature. The sample temperature was calibrated against the thermocouple e.m.f. through a series of lattice-constant measurements on pure silver. 

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