Tungsten analysis

Broadening, of monochromatic beams by crystals, 115, 116, 118 of pulse-size range, 47 Bromine, as internal standard in tungsten analysis, 194-196 determination, by absorption-edge method, 138-142... 

Reduction of WO with thiocyanic acid leads to colored species which have been used for tungsten analysis.193 The color of these species are pH dependent and the structures of some of them are still uncertain. The following sequence of equilibria have been suggested on the basis of several isolated amine salts (equations 7-11).88,194 Of these species, it is believed that the... 

Schmidt reaction of ketones, 7, 530 from thienylnitrenes, 4, 820 tautomers, 7, 492 thermal reactions, 7, 503 transition metal complexes reactivity, 7, 28 tungsten complexes, 7, 523 UV spectra, 7, 501 X-ray analysis, 7, 494 1 H-Azepines conformation, 7, 492 cycloaddition reactions, 7, 520, 522 dimerization, 7, 508 H NMR, 7, 495 isomerization, 7, 519 metal complexes, 7, 512 photoaddition reactions with oxygen, 7, 523 protonation, 7, 509 ring contractions, 7, 506 sigmatropic rearrangements, 7, 506 stability, 7, 492 N-substituted mass spectra, 7, 501 rearrangements, 7, 504 synthesis, 7, 536-537... 

A simple ealibration eurve based on distilled water is suitable for tungsten determination (linearity range is 1-50 mg/dm of W), no interferenee from Fe, Co, Cr, Ni was found. The aeeuraey of the method is eonfirmedby analysis of eertified referenee materials of high alloy steels and niekel based alloys (in range of 0.3 to 15 % W). The analyzed values are agreeing well with the eertified values. 

Samples were tested on in a melt of salts (75% Na SO, 25% NaCl) at 950°C in an air atmosphere for 24 hours. Micro X-rays spectrum by the analysis found that the chemical composition of carbides of an alloy of the ZMI-3C and test alloys differs noticeably. In the monocarbide of phase composition of an alloy of the ZMI-3C there increased concentration of titanium and tungsten is observed in comparison with test alloys containing chemical composition tantalum. The concentration of more than 2% of tantalum in test alloys has allowed mostly to deduce tungsten from a mono carbide phase (MC) into solid solution. Thus resistance of test alloys LCD has been increased essentially, as carbide phase is mostly sensitive aggressive environments influence. The critical value of total molybdenum and tungsten concentration in MC should not exceed 15%. 

Such significant increase of accuracy may be explained on the base of analysis of the numerical values of the theoretical correction coefficients and calculated for 1, , and for analytical pai ameter lQ.j,yipj.j,jj- Changing from lines intensities for the ratios of analytical element line intensity to the intensity of the line most effecting the result of analytical element (chromium in this case) measurement enables the decreases of the error 5 or even 10 times practically to the level of statistics of the count rate. In case of chromium the influencing elements will be titanium, tungsten or molybdenum. 

A composite material used for rock-drilling bits consists of an assemblage of tungsten carbide cubes (each 2 fcm in size) stuck together with a thin layer of cobalt. The material is required to withstand compressive stresses of 4000 MNm in service. Use the above equation to estimate an upper limit for the thickness of the cobalt layer. You may assume that the compressive yield stress of tungsten carbide is well above 4000 MN m , and that the cobalt yields in shear at k = 175 MN m . What assumptions made in the analysis are likely to make your estimate inaccurate ... 

Tungsten ores often contain traces of molybdenum that need to be determined before the ore is processed. When the tungsten content is known, as it usually is, that element can serve as a built-in standard for the determination of molybdenum. In the work to be described, the intensity ratio was measured for molybdenum Ka and tungsten Lyl. The general approach thus resembles that of Eddy and Laby to the analysis of brass (7.10), but conditions are less favorable in the present instance. The background corrections necessary were somewhat involved, and they will be discussed in Chapter 8. See Figure 8-1 c. 

Size Distribution Curves for Three Methods of Particle Size Analysis — Tungsten M-10... 

Theoretical Analysis of Resonance Tube , The Singer Company, Final Report KD 72-82 (1972) 58) F.J. Valenta, The State of the Art of Navy Pyrotechnic Delays , Expls Pyrots (The Franklin Institute Research Laboratories) 5, Nos 11 12 (Nov-Dec 1972). See also Ref 144, pp 185—95. See also Some Factors Affecting Burning Rates and Variability of Tungsten and Manganese Delay Compositions , Ref 144, pp 157—83. See also Mil Spec for Tungsten Delay Compositions , MIL-T-23132A (June 1972) 59) C.F. Parrish et al, Radiation... 

A second unusual EPR spectrum was observed in the oxidized (as-isolated) protein (Fig. 3). This spectrum, which was assigned to an S = z system, was not reminiscent of any Fe-S cluster. Indeed, with g-values of 1.968, 1.953, and 1.903, it looked more like a molybdenum or tungsten spectrum. However, chemical analysis ruled out the possibility that this EPR spectrum arose from Mo or W, and the spectrum was assigned to an Fe-S center instead. The spin concentration, however, was sub stoichiometric and sample-dependent. Furthermore, when the as-isolated protein was oxidized with ferricyanide, it became EPR silent. This, together with the iron determination and the fingerprint of the reduced protein, led Hagen and colleagues to the... 

The hrst mechanism specihcally for tungsten CMP was proposed by Kaufman et al. [67]. They thought, first, chemical action dissolves W and forms a very thin passivating him which stops growth as soon as it reaches a thickness of one or a few moleculars later. Second, the him is removed locally by the mechanical action of abrasive particles, which contact with the protrude parts of the wafer surface, and then cause material loss. In recent years, most of the analysis and models for metal CMP are built based on the Kaufman model [68,69]. However, the model is not involved in microscopic structure analysis for the polished surface, but focuses on interpreting macroscopic phenomena happening during CMP [18]. 

Langmuir s research on how oxygen gas deteriorated the tungsten filaments of light bulbs led to a theory of adsorption that relates the surface concentration of a gas to its pressure above the surface (1915). This, together with Taylor s concept of active sites on the surface of a catalyst, enabled Hinshelwood in around 1927 to formulate the Langmuir-Hinshelwood kinetics that we still use today to describe catalytic reactions. Indeed, research in catalysis was synonymous with kinetic analysis... 

SEM and EDS analysis of the platinum-doped tungsten oxide photocatalyst after sintering showed the presence of platinum particles on the surface of the tungsten oxide. 

Figure 4 is a back-scattered electron image of the sintered platinum-doped tungsten oxide photocat yst (the bri t spheres are platinum). Analysis of the sintered platinum-doped tungsten oxide by ESCA reveal that the platinum the surface is Pt. ... 

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