Stabilisation treatments

For strain-hardenable alloys of the 1000 and 3000 series, the pitting depth is normally lower in soft tempers than in strain-hardened tempers in the latter, the pitting depth increases with strain hardening from H12 to H19. The same apphes to 5000 series alloys with a magnesium content not exceeding 3.5%. Above this concentration, a tendency to intercrystalline corrosion is observed, which increases with strain hardening. This tendency to intercrystalline corrosion can be limited by a stabilisation treatment (H3X) [13]. Alloys of the 6000 series show a resistance to atmospheric corrosion that is comparable to that of 3000 and 5000 series alloys. 

A complex gathering station may include facilities to separate produced fluids, stabilise crude for storage, dehydrate and treat sales gas, and recover and fractionate NGLs. Such a plant would also handle the treatment of waste products for disposal. 

Treatment of Manic—Depressive Illness. Siace the 1960s, lithium carbonate [10377-37-4] and other lithium salts have represented the standard treatment of mild-to-moderate manic-depressive disorders (175). It is effective ia about 60—80% of all acute manic episodes within one to three weeks of adrninistration. Lithium ions can reduce the frequency of manic or depressive episodes ia bipolar patients providing a mood-stabilising effect. Patients ate maintained on low, stabilising doses of lithium salts indefinitely as a prophylaxis. However, the therapeutic iadex is low, thus requiring monitoring of semm concentration. Adverse effects iaclude tremor, diarrhea, problems with eyes (adaptation to darkness), hypothyroidism, and cardiac problems (bradycardia—tachycardia syndrome). 

T.T.S curves as those in Fig. 3.21 can be developed for material cooled very rapidly following solution treatment but the C curve range is a OO-550°C and the nose is at very short times. Freedom from sensitisation in welding can be obtained by ensuring extremely low carbon (and nitrogen) but such levels are not commercially feasible. Stabilisation by niobium and titarium is feasible, but higher ratios are needed than with austenitic steels. With most of the super ferritic group a combination of a practical low carbon level and titanium addition is used. 

The evaluation of heat treatments or the effectiveness of stabilisation by limiting carbon content of these stainless steels can be determined by subjecting specimens to the ASTM standardised acid copper sulphate test or boiling nitric acid test (ASTM A262 1986 see also Sections 9.5 and 1.3). 

Brown has pointed out that Du Pont use evaluation tests for (a-) as-received unstabilised alloys containing more than 0-03% C to check the effectiveness of the final heat treatment and (b) stabilised or special low-carbon grades after a sensitising treatment (1 h at 677°C) to determine whether susceptibility might develop during a subsequent welding operation. 

Catalytic cyclopropanation of alkenes has been reported by the use of diazoalkanes and electron-rich olefins in the presence of catalytic amounts of pentacarbonyl(rj2-ris-cyclooctene)chromium [23a,b] (Scheme 6) and by treatment of conjugated ene-yne ketone derivatives with different alkyl- and donor-substituted alkenes in the presence of a catalytic amount of pentacarbon-ylchromium tetrahydrofuran complex [23c]. These [2S+1C] cycloaddition reactions catalysed by a Cr(0) complex proceed at room temperature and involve the formation of a non-heteroatom-stabilised carbene complex as intermediate. 

Trends in chemical treatment of swimming pool water across Europe are outlined. These relate entirely to the use of dry chlorine, comprising stabilised chlorine and calcium hypochlorite. Results from a recent UK survey are also summarised. 

Applications Quantitative dry ashing (typically at 800 °C to 1200°C for at least 8h), followed by acid dissolution and subsequent measurement of metals in an aqueous solution, is often a difficult task, as such treatment frequently results in loss of analyte (e.g. in the cases of Cd, Zn and P because of their volatility). Nagourney and Madan [20] have compared the ashing/acid dissolution and direct organic solubilisation procedures for stabiliser analysis for the determination of phosphorous in tri-(2,4-di-t-butylphenyl)phosphite. Dry ashing is of limited value for polymer analysis. Crompton [21] has reported the analysis of Li, Na, V and Cu in polyolefins. Similarly, for the determination of A1 and V catalyst residues in polyalkenes and polyalkene copolymers, the sample was ignited and the ash dissolved in acids V5+ was determined photo-absorptiometrically and Al3+ by complexometric titration [22]. 

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