Compound zone

Fig. 2c. Successive intrusive episodes associated with hydrothermal activity can produce compound zones of isotopically altered rocks. The outer O-isotope isopleth is the youngest feature of the reaction zone, and the high 5 0 zone in the hanging wall, the youngest alteration feature overall. Post-hydrothermal intrusions usually lack oxygen isotope alteration.

Compound Zone Position (Zp) Depth d (cm) Zone Dispersion (Zd) d zdb KocC... 

I 70% Evapolation Cooling Crystallization Racemic Compound Zone 11... 

Thin-layer chromatography (TLC) of the sample mixture is most often used to predict the optimum isocratic eluent composition in traditional and modem FC. For rapid elution and separation, the TLC mobile phase should provide an Rf value of 0.15-0.35 for the component of interest, and the difference in Rf values (delta-Rf) should be 0.15 or greater between components to be separated. Rf is defined as the distance traveled by the compound zone divided by the distance traveled by the mobile phase firont. 

Collected FC fractions are analyzed by TLC to determine if the compound of interest is present and to determine its purity. The mobile phase should be reoptimized, if necessary, for separation of the compounds most likely to be present in each fraction. Rf values and detection characteristics of the compound zones separated from fractions are compared with those of standards (if available) developed on the same plate to aid identification of the zones. The ability to apply multiple standards and samples onto... 

Paper with marked compound zones (darker spots) after densitometry... 

Comparative wear tests [27] indicate that the wear performance of bimetattic barret tiners is better than nitrided barrel surfaces, with a predicted improvement in the barrel life of about four to eight times the life of a nitrided barrel. An additional drawback of the nitrided surface is that the hard compound zone is quite thin. Once the compound zone is worn away, wear will increase more rapidly because the diffusion zone is not as hard and wear-resistant. This becomes more severe as the diffusion zone wears away more deeply. 

Pig, 7 Factors affecting the microhardness profile of a nitrided steel. The hard-ness of the compound zone is unaffected by alloy content, while the hardness of the diffusion zone is determined by nitride-forming elements (Al, Cr, Mo, Ti, V, Mn). AX is influenced by the type and concentration of alloying elements AV increases with temperature and decreases with alloy concentration. Source Ref 13... 

Type of metal Designation Nitrkling temperature Surface hardness, HR15N ly al case depth Compound zone thickiiess ... 

---