Refractories chemical composition

Chrome Refractory. A refractory brick made from chrome ore without the addition of other materials the Cr203 content is 25%. and the MgO content is 25%. Chrome refractories are neutral, chemically, and find use as a separating course of brickwork between silica refractories and basic refractories their R.u.L. q.V.) is considerably lower than that of chrome-magnesite refractories. Chemical composition (per cent) Si02 4-7 Fc203, 12-15 AI2O3,16-20 Cr203, 38-42 CaO, 1-2 MgO, 15-20. 

Thermal Properties. Refractories, like most other soHds, expand upon heating, but much less than most metals. The degree of expansion depends on the chemical composition. A diagram of the thermal expansion of the most common refractories is shown in Figure 1. 

Cosmochemistry is the study of the chemical compositions of various solar system materials. Chondrites are the most abundant primitive samples. They are essentially sedimentary rocks composed of mechanical mixtures of materials with different origins (chondrules, refractory inclusions, metal, sulfide, matrix), which we will call components. Chondrites formed by the accretion of solid particles within the solar nebula or onto the surfaces of growing planetesimals. They are very old (>4.5 billion years, as measured by radioactive chronometers) and contain some of the earliest formed objects in the solar system. Chondrites have bulk chemical compositions very similar to the solar photosphere, except... 

The chemical compositions of individual chondrules have been determined by neutron activation of extracted samples or by electron microprobe analyses of chondrules in situ. Some, but not all chondrules are depleted in moderately volatile elements. There is a compositional continuum between the olivine-rich and aluminum-rich chondrules. Original concentrations of the short-lived radionuclide 26A1 in chondrules suggest they formed very early, before all of this isotope decayed, but as much as 2-5 million years after the formation of CAIs (see Refractory Inclusions, below). 

Refractory bricks are divided into two groups according to their chemical composition, based on commercially interesting stones and clays in their natural forms ... 

At the largest scale, the DOM pool can be resolved into four functional pools labile, semilabile, recalcitrant, and refractory (Fig. 6). This classification reflects both chemical composition, measured in units of intermediatory... 

The procedures used to analyze catalysts quantitatively are no different than those for any other chemical material. Often special procedures are needed to dissolve catalysts in preparation for analysis, particularly refractory materials such as certain noble metals and ceramics. The reader should refer to the large body of analysis information available for analyzing the chemical composition of a catalyst of interest. 

There is evidence from chondrites that the solar nebula was well mixed between 0.1 and 10 AU during its first several million years of the evolution, as shown by the homogeneity in concentrations of many isotopes of refractory elements (Boss 2004 Chapter 9). This is likely caused by the evaporation and recondensation of solids in the very hot inner nebula, followed by outward transport due to turbulent diffusion and angular momentum removal. Materials out of which terrestrial planets and asteroids are built have been heated to temperatures above 1300 K and are thus depleted in volatile elements. The inner solar nebula, with some exceptions, does not retain memories of the pristine interstellar medium (ISM) chemical composition (Palme 2001 Trieloff Palme 2006). 

Chemical Composition of Three Classes of High Chrome Oxide Refractories Used in Air-Cooled Slagging Gasifiers (wt%)... 

TABLE 8.21. Properties of Refractories and Insulating Ceramics (a) Chemical Composition of Typical Refractories... 

Chemical compositions of chondrules have been determined from extracted samples using neutron activation analysis and by in situ analysis in polished sections using electron microprobe and ion probe analysis (see e.g., Gooding et al, 1980 Grossman et al, 1988 Alexander, 1995). Chondrules typically show flat refractory abundances that are relatively close to the mean chondrite value and abundances of moderately volatile elements that scatter more widely about the mean. Type II chondrules are relatively unfractionated with near-CI levels of refractories and moderately volatile elements. However, type I chondrules show systematic depletions of moderately volatile elements and a broader spread of refractory abundances with the silicon-rich type IB chondrules being poorer in refractories than the silicon-poor type IA chondrules (Figure 18). The source of the fractionations in type I chondrules is discussed below. 

Weber D. and Bischoff A. (1997) Refractory inclusions in the CR chondrite Acfer 059-El Djouf 001 petrology, chemical composition, and relationship to inclusion populations in other types of carbonaceous chondrites. Chem. Erde 57, 1-24. 

Mao X.-Y., Ward B. J., Grossman L., and MaePherson G. J. (1990) Chemical compositions of refractory inclusions from the Vigarano and Leoville carbonaceous chondrites. Geochim. Cosmochim. Acta 54, 2121—2132. 

Simon S. B., Grossman L., Krot A. N., and Ulyanov A. A. (2002) Bulk chemical compositions of Type B refractory inclusions. Lunar Planet. Sci. XXXin, 1620. Lunar and Planetary Institute, Houston (CD-ROM). 

In this chapter we summarize what we know about the chemical composition of Mercury, with emphasis on assessing the amount of FeO in the bulk planet. FeO is a particularly useful quantity to evaluate the extent to which Mercury is enriched in refractory elements, because its concentration increases with decreasing temperature in a cooling gas of solar composition (e.g., Goettel, 1988). We then examine models for the composition of Mercury and outline tests that future orbital missions to Mercury will be able to make. 

Figure 6 Volatile/refractory element ratio-ratio plots for chondrites and the silicate Earth. The correlations for carbonaceous chondrites can be used to define the composition of the Earth, the Rb/Sr ratio of which is well known, because the strontium isotopic composition of the BSE represents the time-integrated Rb/Sr. The BSE inventories of volatile siderophile elements carbon, sulfur, and lead are depleted by more than one order of magnitude because of core formation. The values for Theia are time-integrated compositions, assuming time-integrated Rb/Sr deduced from the strontium isotopic composition of the Moon (Figure 8) can be used to calculate other chemical compositions from the correlations in carbonaceous chondrites (Halliday and Porcelli, 2001). Other data are from Newsom (1995).

---