Ceramic beads, temperature

The heat transfer medium of the exchanger consisted of 1.6 mm (1/16") diameter, type A, 90% aluminum oxide ceramic beads (Coors Ceramic Co., Golden City, CO) with a specific gravity of 3.6 g/cm. Selected roasting conditions were maintained by control of bead temperature and resident time. The beads were heated to 240°C and were maintained in the chamber with the raw beans for 100 seconds in a 1 5 ratio of beans to beads. These processing conditions resulted in an exit temperature of the beans of 113°C. Roasted beans were cracked through a corrugated roller mill (Ferrell... 

Powders containing bismuth compounds have long been used for decorative purposes to generate a shiny luster or lustrous colors (e.g., facial cosmetic powder in ancient Egypt, imitation pearls made by coating glass and ceramic beads). Bismuth oxychloride [7787-59-9], BiOCl, Mr 260.4, was the first synthetic nontoxic nacreous pigment. It is produced by hydrolysis of acidic bismuth solutions in the presence of chloride ions. Precipitation conditions may be varied (concentration, temperature,... 

Catalytic (Pellistor) Flammable gases Air Measures the heat output due to the catalytic oxidation of flammable gas molecules. A stream of the sample is passed over the sensor which is usually a ceramic bead impregnated with Pt or Pd. The temperature variations in the sensor due to reaction are monitored. Dependent on individual design. Flammable gas detector. Usually portable... 

Figure 3. Temperature profiles for 9.5-mm ceramic beads Re = 120, Pcrf (ooj =...

Figure 7. Temperature-programmed GLC of N-diethylphosphate amino acid methyl ester derivatives [(EtO)2 PO NH CH(R)-COOMe. RbgSO -coated ceramic bead in a Barber-Colman FID. 5% Carbowax 20M on Chro-mosorb W, AW-DMCS, 60/80 mesh in a 2-m by 2.5-mm i d. Pyrex U-tube.

The LDR is 1 O. The disadvantages are that it is sensitive to detector temperature changes, and precise flow control of the hydrogen and air is needed. It is the same as an FID with the addition of a small ceramic bead containing KCI placed just above the end of the burner. 

Thermosets, beads, flakes, ceramic particles, Elevated temperature strength... 

The advantage is an oxidation temperature of 500°F compared to non-catalytic combustion of 1500°F. The active ingredients used were platinum, as well as the base metal oxides of cobalt, nickel, manganese, chromium, and iron. The support material included nickel-chromium ribbons, ceramics rods, beads, and pellets (13-17). 

Figure 1 shows a schematic (elevation) of the Plastofrost apparatus as modified for the present study. The two main components are the heater and the coking attachment. The heater consists of a nickel-plated copper slab in which four 300 watt cartridge heaters are enclosed. A chromel/alumel thermocouple insulated with ceramic tubing placed 5 mm beneath the top surface of the slab measures the temperature (see Fig. 1). The bead of the TC is at the centre of the slab. Figure 2 is a photograph of the assembled apparatus.

The instrumentation for fabrication of the ET normally employs a thermistor as a temperature transducer. Thermistors are resistors with a very high negative temperature coefficient of resistance. These resistors are ceramic semiconductors, made by sintering mixtures of metal oxides from manganese, nickel, cobalt, copper, iron and uranium. They can be obtained from the manufacturers in many different configurations, sizes (down to 0.1-0.3 mm beads) and with varying resistance values The best empirical expression to date describing the resistance-temperature relationship is the Steinhart-Hart equation ... 

Three-dimensionally ordered macroporous ceramic with high LR ion conductivity was prepared by colloidal crystal templating method using monodispersed polystyrene beads [12]. Monodispersed polystyrene beads with 3 pm diameter were dispersed in water and then filtrated by using a membrane filter under a small pressure difference. After this treatment, polystyrene beads were accumulated on the membrane filter with closed pack structure, as shown in Fig. 4.2. Then, the membrane consisting of accumulated polystyrene beads was removed from the membrane filter and put on a glass substrate. After drying at room temperature, the... 

A very drastic and common deactivation phenomenon with automotive emission control catalysts is the irreversible mechanical destruction of the support during road use by breakage in the case of ceramic monoliths, by telescoping of the matrix or breakage of the foil in the case of some metallic substrates and, formerly, by attrition in the case of bead catalysts. With ceramic monoliths, sudden temperature changes can cause thermal stresses and consequent breakage. 

Examples of the uses of ceramic particles in a matrix (rather than as a powder) include the use of glass beads for hardening rubber for tires and adding kaolin to paper to make it smoother and easier to print on. The properties depend not only on the particle but also on the PB that encloses it. Particles are used to seed crystallization and other phase transformations. Hematite particles can be used to seed the growth of a-Al203 at temperatures lower than the usual phase transformation so that the grain size can be kept small. 

---