Copper spheres

Figure 9.8. Sintering of single-crystal copper spheres to a single-crystal copper substrate.

Second, the cold-plate underside consists of highly porous media composed of silver-bonded copper spheres that transfer thermal energy through conduction and aid convective heat transfer to the coolant. Heat-transfer capability is greatly... 

Tsukhanova and Sha-patina (1943) Chukhanov and Sha-patina (1946) 99 C Air Steel, chamotte, copper Spheres, cylinders, granules 2-7 ... 

Example 2.3 For a normal impact between a polyethylene particle (dp = 1 cm) and a copper wall, estimate the critical normal collision velocity of the particle, above which plastic deformation would occur. The yield strength for polyethylene is 2 x 107 N/m2 and the yield strength for copper is 2.5 x 108 N/m2. What would be the critical normal collision velocity for a copper sphere colliding with the copper wall ... 

Example Calculation, Small Bi Case Cooling of a Copper Sphere in Air... 

Fig. 8. (a) Transmission electron micrograph of a Cu/ZnO = 30/70 binary catalyst (40) 60 A copper spheres are placed on crystalline zinc oxide network, (b) Dark field image of the copper crystallites in the area shown in the bright field image (a) obtained using the [111] reflection of copper. [Adapted with permission from J. Catal. 57, 339 (1979). Copyright (1979) Academic Press, New York.]... 

A copper sphere 4.0 cm in diameter is maintained at 70°C and submerged in a large earth region where k = 1.3 W/m - °C. The temperature at a large distance from the sphere is 12°C. Calculate the heat lost by the sphere. 

A copper sphere initially at a uniform temperature T0 is immersed in a fluid. Electric heaters are placed in the fluid and controlled so that the temperature of the fluid follows a periodic variation given by... 

A 5-cm-diameter copper sphere is initially at a uniform temperature of 250°C. It is suddenly exposed to an environment at 30°C having a heat-transfer coefficient h = 28 W/m2 - °C. Using the lumped-capacity method of analysis, calculate the time necessary for the sphere temperature to reach 90°C. 

Black-Globe temperature the temperature inside a hollow copper sphere 15.2 cm (6 in.) in diameter painted matt-black on the outside and containing a thermometer inserted so that its sensing unit is at the center of the sphere. This temperature is a measure of the intensity of radiant heat from the surroundings or the sun. 

A method of preparing narrowly classifies powder has been described by Muta et. al. [129]. A fine copper powder of approximately the required size is mixed with twenty times as much calcium carbonate and heated for 10 minutes at 1100°C in a hydrogen atmosphere. The calcium carbonate is then dissolved out using a solution of 10 parts water to 1 part concentrated nitric acid by volume. The copper spheres so produced had a mean diameter of 6 pm and 80% by weight lay in the size range 1.4 to 10.5 pm. This method was also used by Colon et. al. [130] for the production of glass spheres. 

Names copper spheres, copper powder, bronze powder, brass powder... 

Special methods of incorporation for delustering, titanium dioxide is added to polymer at 210°C to avoid excessive agglomeration the order of addition of glass fiber to PP/PA-6 blend affects blend mechanical performance, glass fiber must be added to already compatibilized blend to avoid filler encapsulation the use of vacuum hopper and premixing of polymer with copper spheres causes a reduction in porosity of highly filled polyamide ... 

Colver and Howell (1980) used the electrostatic EPS (Electric Particulate Suspension) to measure diffusion of spherical copper spheres (74-88 and 125-147 pm) along a copper parallel plate duct having a 1 cm separation distance. The particles were dynamically suspended in the duct by inductive charging... 

Corbett, R. P., The Influence of Powder Resistivity and Particle Size on the Electrostatic Powder Coating Process," in Elektrostatische Aufladung. Dechema-Monographien Nr. 1370-1409, DECHEMA, Frankfourt, 1974, pp. 261-271. Cotroneo, J. A. and G. M. Colver, Electrically Augmented Pneumatic Transport of Copper Spheres at Low Particle and Duct Reynolds Numbers, J. Electrostatics, 5, 1978, pp. 205-223. 

A polymer solution at 25°C flows at 1.8m/s over a heated hollow copper sphere of diameter of 30 mm, maintained at a constant temperature of 55°C (by steam condensing inside the sphere). Estimate the rate of heat loss from the sphere. The thermophysical properties of the polymer solution may be approximated by those of water, the power-law constants in the temperature interval 25 < J < 55°C are given below n = 0.26 and m = 26 — 0.0566 T where J is in K. What wiU be the rate of heat loss from a cylinder 30 mm in diameter and 60 mm long, oriented normal to flow ... 

Whereas the scaling laws appear of be obeyed reasonably well in simple metallic systems, e.g., nickel wires, copper spheres, and silver spheres, the application of the laws to the sintering of AI2O3 produced unexpected results (8). For powders with a narrow size distribution, high nonintegral values of the exponent m were found. The value of the exponent also varied with the extent of densification, especially in the early stages of sintering. 

Figure 8.12 Data for (a) neck growth and (b) shrinkage of copper spheres. The exponents are characteristic of those for lattice diffusion. (From Ref. 12.) Later analysis of the data showed that surface diffusion was the dominant mechanism with a major contribution from lattice diffusion that gave shrinkage (see Fig. 8.23).

Figure 8.23 Neck size sintering diagram for copper spheres. The data of Kingery and Berg (12) are also shown. (From Ref 37.)...

---