Growth Mechanism and Crystal Form of Potassium Dichromate
The structure of potassium dichromate (P1, Z = 4) consists of two layers parallel to (001), between which no crystallographic symmetry relation exists. These layers are nearly coincident with each other when rotated through 90° about c * . One question remained unanswered: do the crystals grow parallel to {001} with d(002) or d(001) layers? The pseudo-fourfold axis does not run parallel to a crystallographic direction and acts only between two layers. This means that crystal growth parallel to {001} occurs in d(001) layers, which corresponds to the occurrence of one-sided intergrowths on (001). The layers are also nearly coincident with each other through pseudo-twofold axes parallel to [110] and [110], These axes do not act in the (100) or (010) projections. In the projections along the [110] and [110] directions, the lattice directions are then extended by a factor of approximately √2, and the formula units in the cell of the d(002) layer are doubled. This indicates a further possible growth mechanism. The theoretical growth forms of the crystals were calculated with the Fourier transform method of morphology.
The structure of coarse crystal surfaces : the (0 0 1) face of K2Cr2O7 crystals grown from aqueous solution as an example
Abstract The surface structure of the coarse (0 0 1 ) face of potassium bichromate (K2Cr2O7) was studied in-situ and ex-situ with the help of optical microscopy, atomic force microscopy and scanning electron microscopy. A multitude of features, like unit cell height steps, bunches, macrosteps of which some are actually small facets, inclusions and spirals were observed. The observations lead to new ideas about the growth mechanisms of this face, in which the combined action of impurity adsorption and volume diffusion plays a key role. These mechanisms may be responsible for the coarse growth on other crystals as well.
CNC Desktop Vertical Machining Bench Design and Cooling Fluid Application
Today's manufacturing technologies, the human work force is used and at least a minimum level of margin of error is used in CNC machines. Desktop CNC machine tools and CNC machine tools are developed in parallel with the development of personal computers. This study provides CNC training institutions for education, small and medium-sized enterprises for commercial purposes use the low-cost desktop machine has been designing and manufacturing of CNC vertical machining was carried out. Desktop CNC machine tools and production capacity to handle the kind of material was applied to increase the cooling fluid. Through A199 and Fe37 the cooling fluid application desktop CNC machine tools, such as processing of materials that are difficult to successfully processed. Keywords—CNC, Desktop CNC Machine, CNC Design