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Two dimensional ultrasonic vibration assisted grinding (TDUVG) is analyzed based on theoretical analysis of the cutting trace of a grain in the finished surface, and it gives the kinematical model of single grit during TDUVG, and the condition of the separate cutting is established, so two dimensional ultrasonic vibration are introduced into the system, which helps to form good machining way.
Tab. 1 Experimental conditions parameters Experimental conditions wheel diamond wheel (resin bond, grain size: w20), size：Φ350×Φ127×35mm Wheel dressing The grinding wheel truing : 200#SiC, the grinding sharpening: #400Al2O3 Ultrasonic vibration The amplitude A: 10.2µm, the amplitude B: 11.9µm, its frequency f: 20.3KHz, its power: 80W Grinding parameters Wheel speed vs:26.6m/s,axial feeding speedva: 3mm/pass, grinding depth ap: 2(µm), worktable speed vf: 5, 15, 25(m/min) wokpiece nano-ZrO2 ceramics, which are sliced bars with dimensions of 25 mm×15 mm×8 mm Cooling method Dry grinding Experiment method.
It causes the separate cutting, and many abrasive particles’ elliptical vibration grinding take the polishing action on finished surface, and it may enlarge grinding groove of single abrasive grain, and increase interference among abrasive grains, as a result, TDUVG has the characteristics of rotating cutting, so it keeps the sharpness of grinding wheel, raises the service life of diamond grinding wheel, increases the number of effective grain, reduces the mean grinding force which may reduce the generation of the crack and fracture of the finished surface, expands the plastic wording zone of materials, thus, it may improve surface quality of the finished surface.
(a) TDUVG (vf=5m/min) (b) TDUVG (vf=15m/min) (c) TDUVG (vf=25m/min) (d) DG (vf=5m/min) (e) DG (vf=15m/min) (f) DG (vf=25m/min) Fig.4 SEM photographs of the finished surface of nano-ZrO2 with different worktable speed Summary To further the understanding of the basic mechanism of the ultrasonic machining of ceramics, TDUVG is analyzed based on the cutting trace of a grain in the finished surface, which proves two dimensional ultrasonic vibration help to form the separate cutting which improve the surface quality of workpiece.

And the equiaxed grain zone is formed when the distance is increased above 0.75mm as the effective heat flow decreased.
In addition, the further growth of the columnar crystals is prevented by equiaxed grains.
The proportion of equiaxed grain zone is about 25%.
Thus, a large number of small equiaxed grain formed in the zone close to the mould wall.
Therefore, equiaxed grains are formed in the front of columnar crystals and the growth of columnar crystals stop.

Table 1 shows the grain size composition of the sand.
The number of the samples in each group was taken equal to five.
Filler grains in dry mixes for smooth application, for example, putties and mortars for tile joints, have a grain size of no more than 0.1 mm.
In accordance with Scheffe's simplex-lattice plan and the number of experiments 10, the following variable factors were taken: Х1 – sand fraction with a particle size of less than 0.16 mm; Х2 – sand fraction with a grain size of 0.16–0.315 mm, Х3 – sand fraction with a grain size of 0.315–0.63 mm.
In accordance with Scheffe's simplex-lattice design and the number of experiments 10, the following variable factors were taken: Х1 – content of sand fraction with grain size 0.315–0.63 mm; Х2 is the content of the fraction of sand with a grain size of 0.16–0.315 mm; Х3 is the content of chrysotile.

A visual analysis of the number of carbide inclusions shows that after quenching their number increased.
The study has shown that the structure of the layer of U8A steel after annealing consists of a ferrite matrix and cementite extractions along the grain boundaries.
The layers formed by different steels differ in the number of carbide particles.
In our opinion, this is due to the presence of obstacles for grain growth.
We have determined that during heat treatment the size of the carbide inclusions decreases and their number increases.

Hysteretic temperature effects can have a significant cumulative effect on a structure due to the large number of thermal cycles the material may experience in its operational lifetime.
The cycle number chosen was 400.
The most energetic area is located within grain center, therefore, the grain boundary diffusion and subsequent formation of sintering neck is less favored.
It is widely accepted that microcracks depend on the grain size of b-eucryptite, and there is a critical grain size below which microcracks do not occur [3,9-11].
Bruno et al. [10] found that different grain sizes induce microcracking at different temperatures (~500 ºC for large grains, 20-30 mm, and 300 ºC for medium grain sizes, 5-10 mm).

Such shorter high temperature is important to prevent grain growth.
The microstructures of the alloy contains equiaxed gamma TiAl with sub-micron grain size and small amount alpha Ti3Al phase.
Actually the existence of Al2O3 on the Ti3Al grain boundary suppresses its grain growth .
As a result, in addition to defects such as stored internal strain and stored dislocation, closed micro pores formed during milling seemed to cause an increase of grains after sintered.
Mean that liquid phase sintering of Ti55Al45 powder should be carried out at low temperature as possible to obtain fine grains.

Theoretically, in a semi-infinite system A,B, the number of monomineral zones which are formed is equal to the number of intermediate compounds likely to be formed between the phases A and B.
Gibbs(13) can be used to predict the number of phases of the system.
In this case the phase number must be necessarily lower or equal to 3.
The phase number is then equal to 3 (f = 1 liq. + 2 sol. = 3) and the variance to 0 (V = 0).
The phase number is then equal to 2 (f = 1 liq. +1 sol. = 2) and the variance to 1 (V = 1).

The obtained results are compared with the existing models and a new model that relates the fracture toughness to a number of microstructural parameters and basic tensile properties is developed. 2.
Details of different precipitates are shown in Fig. 1a: a homogeneous distribution of small precipitates within grain, with relatively coarse and closely spaced G-Mg(Cu,Al,Zn)2 particles [1,2] at the grain boundary.
Coarse grain boundary precipitates could be seen within some of them.
They appear to be formed from the grain boundary, but fracture following these linear features cannot be entirely intergranular, i.e, linkage of grain boundary failure is partly transgranular (33.5% of fracture surface).
In this respect, Eq. 1 is used as a starting expression of the new proposed model, since a key validation point for Hahn and Rosenfield model [6] was the fv-1/6 dependence observed in a number of Al alloys.

A single number can be more than a quantity for one certain measurand.
The laps are made of metal for the coarse grains and made of glass for the fine grain sizes.
With smaller grain sizes, glass laps are used.
Each grain-size has to remove the damage in the surface of the previous step with larger grain-size completely.
This overcomes the problems with diffraction and allows a large number of diameters to be measured at the same time.

The SEM image of 304 stainless steel without etching is shown in Fig. 1.As seen in the Fig 1,the size of austenitic grain is found to be in the range of approximately 5 to 10μm .
Some ridges whose orientation is different within different grain are observed in the grains .These ridges are ladder formed by slide of adjacent thin layer, due to the mechanical polishing process in surface [15].
Fig. 2 SEM micrographs of the 304 stainless steel surface etched in different time (a)electrolytically etched 20s (b)electrolytically etched 35s (c)electrolytically etched 50s (d)chemically etched 40s (e)chemically etched 80s (f)chemically etched 120s Fig. 2 shows the SEM micrographs of the 304 stainless steel surface etched in different time.As shown in Fig. 2 (a),(b) and (c),austenite grain boundaries can be observed clearly.A large number of compact, uniform holes which looks like honeycomb are distributed in these grains.During etching time,the hole size (in the range of 0.3-0.6 μm ),hole density increase gradually.
grain boundaries of substrate is.
This is because the “block-discontinuous” structure is conducive to the release of stress on the grain boundaries and relive of the fracture that make coating spall .This case is similar to“fine grain strengthening” mentioned in Metallography:The finer the grain size was ,the smaller stress concentration and the harder expansion the crack is.