Pyrometric cones

Pyrometric cones Pyrometry Pyronaridine [74847-35-1] Pyromne B [2150-48-3] Pyromne G Pyrophosphatases Pyrophosphates... 

Refractoriness. Most refractories are mixtures of different oxides, sometimes with significant quantities of impurities. Thus, they do not have sharp melting points but a softening range. Refractoriness is the resistance to physical deformation under the influence of temperature. It is determined by the pyrometric cone equivalent (PCE) test for aluminosiHcates and resistance to creep or shear at high temperature (see Analytical methods). 

Refractoriness. Refractoriaess is determined by several methods. The pyrometric cone equivalent (PCE) test (ASTM C24) measures the softening temperature of refractory materials. Inclined trigonal pyramids (cones) are formed from finely ground materials, set on a base, and heated at a specific rate. The time and temperature (heat treatment) requited to cause the cone to bend over and touch the base is compared to that for standard cones. 

Other nonelectrical thermometers are bimetal, fiHed-system, and pyrometric cone thermometers. In bimetal thermometers, two strips of metal of differing expansion characteristics are welded together face-to-face. If one end of such a strip is fixed, the strip bends in response to temperature change as the... 

PYROMETRIC CONES. Small cones that differ in the temperatures at which they soften on heating. They are made of clay and other ceramic materials and are used in the ceramic industries to show furnace temperatures within ranges. In practice, three or four of the cones which... 

Pyrometric cones (Figure 1.1) have been in common use over the past century in the manufacture of ceramic ware. They are a series of fired mixtures of ceramic materials pointing 8° from vertical, which droop after exposure to elevated temperatures for a period of time. The manufacturer [4] provides a series of sixty-four cone numbers ranging from 022 (deformation at 576°C at a heating rate of l°C/min) to 42 (over 1800°C).3 By placing a series of cones near the firing ware in a kiln, the operator can determine when firing of the ware is complete, even when the furnace temperature is only loosely controlled. The refractories industry has made cone shapes out... 

The Properties and Uses of Orton Standard Pyrometric Cones and How to Use Them for Better Quality Ware, Edward Orton Jr. Ceramic Foundation, Westerville, OH (1978). 

Refractory No. °F Pyrometric Cone Deformation under Load % at °F and ib/in.) Spalling Resistance Repeat Shrinkage after 5 hr % °F) Straight 9 in. Brick (ib)... 

Maximum use temperatures are reported on refractory data sheets in terms of pyrometric cone equivalent (pee). In essence, this pee defines the temperature at which a small standard sized cone of the material slumps due to softening. Table 18-1 lists the pee numbers with the corresponding temperature limits and generic types of brick which fall within the various pee ranges. These reported pce s indicate a refractory s maximum use limit when exposed to a gas-fired environment however, they may actually soften at much lower temperatures due to reactions with the atmosphere they are containing. 

Table 18-1 Approximate Pyrometric Cone Equivalent (PCE) Values of Generic Classes of Fireclay and High Alumina Refractory Brick...

The following survey of pyrometric cone softening temperatures for several refractories is given for the purpose of rough orientation ... 

In contrast, magnesite refractories which are comparable with the silica ones as regards the amount of melt, may have lower To.6(1500 —1750 °C) despite a significantly higher pyrometric cone refractoriness. This is due to the granular macro-structure in which the solid particles are separated by layers of low-viscosity melt. 

If the refractoriness of a material is to be determined, it must be cut or shaped into a cone of the same shape which is then heated at the specified rate together with several standard cones. The high-temperature behaviour of an unknown material is thus compared with that of a known material. The refractoriness is then specified by the number of that standard pyrometric cone whose tip would touch the supporting plaque simultaneously with a cone of the refractory material under investigation (pyrometric cone equivalent, PCE). 

The more recently recommended pyrometric scale is analogous to the Seger scale in which the pyrometric cones are designated by the first three numerals of temperature in °C the bottom imit for refractories is number 150 (1500 °C), for high-temperature refractories 177 (1770 C). 

The firing behavior of a clay is determined by making up a series of briquettes, about 2 by 13 by 1 in., placing them in a suitable kiln or furnace and drawing one or more specimens at different temperature intervals. It is necessary, of course, to maintain accurate temperature control by means of a pyrometer or by the use of standard pyrometric cones. It is customary to draw the first specimen at 1,050°C. 

PCE. Abbreviation for pyrometric cone equivalent, a scale of melting or fusion points of refractory materials, based on comparison with the temperature at which pyrometric cones melt. 

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