Temperature cycling, effect

Figure 3, Temperature cycling effect on permeability of annealed AISI 304...

The need for temperature cycling should be taken into account when designing or conducting tests. The nature of the test vessel should be considered for tests in aqueous solutions at temperatures above about 60°C since soluble constituents of the test vessel material can inhibit or accelerate the corrosion process. An inhibiting effect of soluble species from glass, notably silica, on the behaviour of steel in hot water has been shown . Pure quartz or polymeric materials are often more appropriate for test vessel construction. 

Bonomo R.I. Denver, Study on the Effect of Temperature Cycling of High Explosives , AFSWC Report TDR 62-16, Contract No AF 29 (601) 2671 (March 1962) 9) J.D. 

J Temperature cycling tions Domino effects Missile effects... 

The N20 decomposition, CO oxidation, and H2 oxidation reactions are known to exhibit concentration oscillations over noble metal catalysts. Flytzani-Stephanopoulos et al. (47) have observed oscillations for the oxidation of NH3 over Pt. The effects are dramatic and lead to large temperature cycles for the catalyst wire. Heat and mass transfer effects are important. 

A temperature cycling experiment comprising three cycles of —70/50°C with CD and UV spectra recorded at each temperature for 56 indicated that the transition is reversible, with negative and positive Cotton effects being observed at the low and high temperatures, respectively, as is evident in Figure 4.44. 

The atomization temperature is usually chosen so as to give a rapid peak. It should not be so hot as to damage the tube unnecessarily or distil off involatile contaminants, or so cool as to lose sensitivity or create memory effects (although a tube clean, i.e. a high-temperature cycle, can be included in the programme). 

The MRC cycle calls for a 182°C cure temperature. The effect of cure temperature on residual stress was investigated by curing specimens at four other cure temperatures (171, 165, 160, and 149°C) while holding the dwell time (4 hours) constant. In Figure 8.18 the dimensionless curvature for these specimens is plotted versus the cure temperature. The curvature is reduced as the cure temperature is decreased with significant reduction in curvature obtained for dwell temperatures of 165°C or less. The final curvature as predicted by the viscoelastic process model is overlaid with the experimental data in Figure 8.18 and is shown to capture the trend. 

FIGURE 17.9 Inhibition of dissolution and recrystallization of sulfathiazone by PVP. Temperature cycling of 2% sulfathiazole suspensions demonstrating the effect of PVP on dissolution and recrystallization. (Publication by Ziller, K. H. and Rupprecht, H. H. (199 )harm. Ind., 52 1017-1022. With permission.)... 

---