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PIRAC as well as PVD nitriding of Ti alloys at T>800°C may result in coarsening of grain size and as a result in reduction of the fatigue resistance [8].
In the present work, Ti alloys were PIRAC nitrided at the relatively low temperatures of 700-850°C in one and 3 stages with the goal to avoid grain coarsening, obtain thicker TiN based coatings with and keep the excellent adherence of the coating to the substrate.
The coatings produced by the 3 stage PIRAC process show a more gradual change of microhardness as a function of a distance from surface and higher microhardness numbers at the same depth as compared to one stage PIRAC process (see Fig.7) indicating it has a thicker Ti nitride layer.

The microstructure of the as recevied is composed of large number of flake pearlite and small amount of ferrite, it may be caused by higher cooling rate of air cooling after hot rolling and it is not acceptable for plastic deformation.
When the tempering tempreature is lower, such as 540°C and 580°C, the tempered sorbite retains the orientation of the quenched martensite because the sorbite generates along the martensite grain boundary.
It needs larger energy to make this kind of grain sliding which needs larger plastic deformaion force.

In low stress condition, the surface morphology shows a number of voids (Fig.5b-3), indicating that the final failure may be related to the accumulation of these voids.
In high stress condition, grain boundary sliding (GBS) is predominant (Fig.5b-1) and may lead to the final failure.
While grain boundary sliding may be the dominant mechanism leading to failure in the high stress region, the accumulation of voids leads to final failure in the low stress region.

At lower forging temperatures (1000°C), the microstructure consists of primary α and a small amount of primary β grains mixed with a newly formed fine lamellar α-β grains.
Underneath the well defined porous layer the number of pores is gradually decreasing, with few very small remaining pores in the middle part of the discs.

Because according to the Hall-Petch equation, the strength properties of the material rise along with the reduction of the grain size.
In case of the coatings deposited by the PVD and CVD processes, the structures obtained, with grain size ~10 nm cause the obtainment of the maximum mechanical properties.
The produced coatings reveal a number of microparticles in the form of droplets occurred in the structure.

These methods allow growing multicomponent films having an arbitrary number and composition of elements with only one magnetron employed.
The small individual grains were appeared for all of the substrate-to-target distances.
The small grains with triangle shape spread across the surface were investigated for all substrate-to-target distances.

In addition, adding nano-Y2O3 particles promoted the formation of equiaxed grain, due to Cr23C6 and nano-Y2O3 act as heterogeneous nucleation sites in the melting pool.
The large number of easily sheared hcp {0001} planes, which were found parallel to the wear track surface, can be regarded as an explanation for the low friction properties of the laser processed Co-based alloy [16].
It was reported that, Dendrite microstructures were observed perpendicular to the interface of each layer where coarsening of microstructures were obtained as more layers are deposited; at the bonding zone of two layers, equaxied grain appeared locally.

Flotation of fine coal was carried out in a laboratory flotation machine type FL 237 with the number of revolutions of the impeller 1740 per minute, air consumption 1.2 l/min, the volume of the flotation chamber 0.75 liters, in feed solids 100 g/l. as flotation agent is a mixture of lighting kerosene (95 %) and blowing agent T-66 (the VAT residue of rectification of dimethyldioxane) – 5 %, the flow rate of the mixture to 1.0 and 2.0 kg per 1 ton of floated sludge(Table 2).
results of flotation of fine coal (class 0 – 0.5 mm), [%] The composition of the mixture of flotation reagents: kerosene – 95 [%]; T-66 – 5 [%] Consumption mixture, [kg/t] Concentrate Tailings Ash source Е Кс access to: ash access to: ash class Mine class mine mine Denisovsky, Plast К4 1.0 93.4 9.43 10.0 6.6 0.67 41.6 12.1 378 4.3 2.0 95.5 9.65 10.3 4.5 0.45 49.8 11.8 474 5.4 mine Inaglinskaya, Plast D19 1.0 83.1 6.48 10.8 16.9 1.32 67.8 20.4 522 6.6 2.0 89.3 6.97 12.2 10.7 0.83 86.0 19.9 614 7.7 mine Inaglinskaya, Plast D15 1.0 78.3 7.75 9.1 21.7 2.15 53.1 18.7 457 5.6 2.0 85.5 8.46 10.3 14.5 1.44 66.2 18.4 550 6.7 The section of the Western. 1.0 81.6 5.30 10.9 18.4 1.20 59.5 19.2 446 5.5 2.0 87.1 5.66 12.1 12.9 0.84 67.2 19.2 484 6.0 However, the high ash content of flotation concentrate, particularly when the flow rate of the mixture of reactants of 2.0 kg/t of ash-rich flotation concentrate obtained at the expense of mechanical removal in a foam product of fine mineral grains
However, ash content of flotation concentrate for all the layers is considerably higher (9.1 to 12.2 per cent), however, and its output is also higher and is in the range of 81.6 – 95.5 per cent depending on the consumption of flotation reagents (Table 3).The ash content of the flotation concentrate is enhanced by mechanical removal in a foam product of fine mineral grains, which is typical for mechanical (impeller) of the flotation, especially when flotation is sufficient high-ash sludge (about 20 %).

Table 2 Results of orthogonal experiments Trial number Factors Content of ceria in the product (wt %) hydrochloric acid concentration A (mol/L) Reaction time B (min) Reaction temperature C (ºC) 1 1 30 25 56.47 2 1 45 35 56.70 3 1 60 45 56.97 4 2 30 35 64.11 5 2 45 45 70.77 6 2 60 25 65.30 7 3 30 45 72.40 8 3 45 25 68.03 9 3 60 35 72.51 K1 170.14 192.99 189.81 K2 200.18 195.51 193.32 K3 212.94 194.79 200.13 K1/3 56.71 64.33 63.27 K2/3 66.73 65.17 64.44 K3/3 70.98 64.93 66.71 R 14.27 0.84 3.44 In the leaching process, the content of ceria was affected by many factors, such as solid-liquid ratio, concentration of hydrochloric acid (A), time (B) and temperature (C) of leaching etc.
This conclusion coincided with the trend of increasing grain size in the SEM micrographs shown in Fig. 3.
The sample calcined at 800 ºC (Fig. 3b), grain growth was obvious, and the particle size was more than 150 nm.

Phases of the Manufacturing Process During all the test the material grain direction was taken into account, with the aim of the fatigue tests had the same test conditions.
Hence the importance of taking into account in the fatigue tests the grain direction.
Fig. 6 shows the number of cycles to breakage (N) as a function of feed for the different cutting speeds applied.