Copper quenching

Fig. 8.1.3 Rcaclor chamber designed for powder processing studies (1) torch head. (2) three concentric quart/ lubes. (3) work coil, (4) water-cooled Pyrex cylinder. (5) water-cooled copper quenching plate. (6) window, (7) to generator, (8) water in, (9) water out. (10) to exhaust system. (Reprinted front J Mater Sci, 65. The synthesis of ultrafine titanium nitride in an r.f. plasma. Copyright 1979. with kind permission from Kluwer Academic Publishers.)...

Samson G, Morissette JC, Popovic R. Copper quenching of the variable fluorescence in Ounaliella tertiolecta. New evidence for a copper inhibition effect on PSIl photochemistry. Photochem Photobiol 1988 48(3) 329-332. 

Quenching Studies. The solvated electron component at 675 nm was studied under conditions of oxygen and copper quenching (FIGURE 5)> It appears that in our (concentrated) solutions of fulvic acid (200 mg/1), and at elevated laser power (3-30 m.j), it is formed by a one photon process. Conditions for observation of these spectra with excitation at 355 nm and on the nanosecond scale match those cited by previous authors (6 ). Moreover, we were able to observe the solvated electron formation at reduced power (2-3 m.j) on the picosecond scale in (concentrated) solution (200 mg/1), suggesting, at least for our material, that there is no intensity threshold for formation of e solv. 

Fig. 4. Schematic diagrams of (a) piston-anvil quenching (39), where A is the fixed anvil B, the fast-moving piston C, copper disks and H, photo cells (b)...

Hydrocarbon, typically natural gas, is fed into the reactor to intersect with an electric arc stmck between a graphite cathode and a metal (copper) anode. The arc temperatures are in the vicinity of 20,000 K inducing a net reaction temperature of about 1500°C. Residence time is a few milliseconds before the reaction temperature is drastically reduced by quenching with water. Just under 11 kWh of energy is required per kg of acetylene produced. Low reactor pressure favors acetylene yield and the geometry of the anode tube affects the stabiUty of the arc. The maximum theoretical concentration of acetylene in the cracked gas is 25% (75% hydrogen). The optimum obtained under laboratory conditions was 18.5 vol % with an energy expenditure of 13.5 kWh/kg (4). 

Tables 1 and 2, respectively, Hst the properties of manganese and its aHotropic forms. The a- and P-forms are brittle. The ductile y-form is unstable and quickly reverses to the a-form unless it is kept at low temperature. This form when quenched shows tensile strength 500 MPa (72,500 psi), yield strength 250 MPa (34,800 psi), elongation 40%, hardness 35 Rockwell C (see Hardness). The y-phase may be stabilized usiag small amounts of copper and nickel. Additional compilations of properties and phase diagrams are given ia References 1 and 2.

NEW FLUORESCENCE QUENCHING METHOD FOR DETERMINATION OF COPPER (II) IN WATER... 

Fluorescence quenching methods wits ai omatic complexing reagents are often recommended for copper (II) determination in water. 

The alloy aluminium-4 wt% copper forms the basis of the 2000 series (Duralumin, or Dural for short). It melts at about 650°C. At 500°C, solid A1 dissolves as much as 4 wt% of Cu completely. At 20°C its equilibrium solubility is only 0.1 wt% Cu. If the material is slowly cooled from 500°C to 20°C, 4 wt% - 0.1 wt% = 3.9 wt% copper separates out from the aluminium as large lumps of a new phase not pure copper, but of the compound CuAlj. If, instead, the material is quenched (cooled very rapidly, often by dropping it into cold water) from 500°C to 20°C, there is not time for the dissolved copper atoms to move together, by diffusion, to form CuAlj, and the alloy remains a solid solution. 

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