Search results

In Kopalinsky's work, the contact length was used to quantify several grinding parameters, including the contact area of wheel and workpiece, the size of the heat source and the size of the heat flux of rubbing for calculating the grinding temperatures, the size of a set of active grains on the wheel in contact with the workpiece simultaneously in grinding and the time it took for the set to enter the contact region, the number of active cutting edges in the grinding contact area and the number of active rubbing points in the grinding contact area, and the contact time of individual active cutting grains with the workpiece, which demonstrated the importance of the contact length in the analysis of grinding processes.
And consequently the number of active cutting edges in the grinding contact area becomes 26 instead of 14.
Table 2 Comparison of the results based on different contact length models x based on lc, Eq.(1) y based on lg, Formula (1a) x/y Contact length 3.49 mm 1.88 mm 1.855 Contact area 10.5 mm 2 5.64 mm 2 1.855 Number of active edges 26 14 1.855 Maximum grinding temperature [16] ( ) cw w we lckv av T 1Re2.1 max         = ρ ( ) gw w we lckv av T 1Re2.1 max         = ρ 0.734 Conditions used in the analysis [18]: Workpiece martial: En9; Grinding wheel: WA46J with diameter ds of 177 mm; Depth of cut ae: 0.02 mm; Width of cut b: 3 mm: Wheel speed vs: 40 m/s; Workpiece speed vw: 0.5 m/s; Fn': 10 N/mm; Ks: 6.16 10-6 mm2/N; Kw: 1.36 10-6 mm2/N: Rr = 9 Figure 5 is an overview of the contours of rc-g covering a full range of grinding conditions, from fine grinding, shallow grinding, creep-feed grinding to high speed grinding (i.e. q is from 50 to 10000 and ae is from 0.001 to 50 mm).
In summary, an increase of grinding wheel wear and dullness during grinding processes means not only an increase in the area of the wear flats on its grains, an increase in the negative rake angle of the cutting edges as highlighted by Kopalinsky [18], but also a decrease in the real contact length.

The intensity and number of diffraction peaks mainly depend on the amount of corresponding phases.
The band positions and number of absorption peaks are depending on crystalline structure and chemical composition.
The number of peaks in the emission spectrum represents the wavelength of emission.
High frequency semi-circle corresponds to grain resistance (Rg) and low frequency semi-circle corresponds to grain boundary resistance (Rgb).
FTIR spectra depict the band positions and numbers of absorption peaks are depending on the crystalline structure and chemical composition.

The number and orientation of shear planes depend primarily on the number and the concentration of the oxygen vacancies.
With a radius of the Ti4+-ion in the titanium oxides of 0,61 Å (1 Å equals 10 nm) and a co-ordination number of 6 [16] besides Cr3+ primarily (Al, CO, Fe, Nb, Ni, Mn, Mo, Sn, Ta, V, W, Zr) - cations of different valence come into consideration.
The approach of obtaining coating systems of Andersson-type phase content by mixing two oxide ceramics in the plasma requires knowledge about the grain size of the powders being used.
Therefore the SPS process seems to be suitable particularly to mix a larger number of oxide ceramic systems in the plasma and to examine the resulting phase content concerning its suitability regarding the requirements.
Birringer: Estimating Grain-Size Distributions in #anocrystalline Materials from X-ray Diffraction Profile Analysis, Phil.

However, in order to ensure the steady growth of grain production chemical fertilizers, pesticides applied by large-scale in the agricultural production, has resulted in extreme deterioration of water environment in rural areas; with industrial and urban life has been gradually control point source pollution, agricultural non-point source pollution has become China's water contamination of the first subject.
According to the latest agricultural condition of China's Ministry of Agriculture shows that in 2011 China's autumn harvest is a foregone conclusion, the annual grain production is expected to total 11,000 billion kilograms onto a new level, for eight consecutive years to achieve production, yield and total production will hit a record high [ 4].
Although the harvest for eight consecutive years, China's grain production and demand gap is still relatively large, face to domestic land, water resources and ecological environment and other ristrict factors, more and more global climate change, extreme weather events continue to happen in today's , in period of the "twelve five plan", water, soil and other agricultural resources, security issues will be particularly prominent.
According to the multifunctionality of agriculture, between the government and the farmers' principal-agent relationship, farmers (agents) in fact assume a number of tasks of the government (principal), or the agent's work more than one dimension or the target, because this article has multiple functions of agriculture and food production capabilities, simplify food safety and environmental features, and accordingly, the government (the client) commissioned farmers (agents) there are also two target.

Considerable attention has also been focused on the incidence of a number of non-infectious diseases common in civilized societies, such as coronary heart disease, which could be attributed to a low DF intake.
[3] McKeown NM, Yoshida M, Shea MK, et al.: Whole-grain intake and cereal fiber are associated with lower abdominal adiposity in older adults, J Nutr.139 (2009) 1950-1955
[4] Qi L, van Dam RM, Liu S, Franz M, Mantzoros C, Hu FB.Whole-grain, bran, and cereal fiber intakes and markers of systemic inflammation in diabetes women, Diab Care. 29 (2006) 207-211
[6] Bazzano LA, Song Y, Bubes V, et al.: Dietary intake of whole and refined grain breakfast ceral and weight gain in men, Obes Res. 13 (2005)1952-1960

In the grinding of brittle materials, it is well documented that grinding can occur in the ductile regime if the maximum depth of cut of individual abrasive grains is less than the critical depth of penetration that causes brittle fracture in a material.
The maximum undeformed chip thickness (hmax) represents the maximum depth of penetration of the active abrasive grains into the workpiece in the grinding event. hmax is determined by the bonding material, the depth of cut, wheel velocity, workpiece speed and the cutting tool geometry, can be calculated by [7-8]: (5) where E1 is the elasticity modulus of the grinding wheel; E2 is the modulus of elasticity of the workpiece; r is the chip width-to-thickness ratio (it was suggested that the range of r is 10-20); C is the grain surface density which is usually defined as the number of active points per area of the grinding wheel surface; Vw is workpiece feed rate; Vs is wheel speed; ae is the depth of cut; and deq is the equivalent wheel diameter.

However, the above method is strictly applicable for crystallographically untextured films exhibiting isotropic grain interactions [2].
For textured thin films, the most general approach of stress analysis is to use of the so-called X-ray stress factors involving the crystallographic orientation distribution function (ODF) with appropriate grain interaction model [2,3] which is cumbersome in practice.
For fiber textured specimen, in case of plane rotationally, symmetric state of stress the simplified sin2y law have been derived assuming Reuss type of grain interactions in the specimen.
Some of the major reasons are: (i) simultaneous presence of strong and sharp fiber texture in Ti films deposited for 15min. leads to small number of data points in the plots (Fig.2(c)) which makes the stress analysis unreliable; (ii) use of so-called X-ray diffraction elastic constants in stress analysis does not take into account of crystallographic texture in the films and thus can lead to serious errors in stress values; (iii) large data scatter in CGM plot (Fig.3(a)) may lead to erroneous stress values.

In accordance with the selected model, the lost mass М of a tool was evaluated by the following formula: М = Ka·ρ·Fa· (Ј·σa/σp), where Ka is the adhesion coefficient (volume); ρ is the density of tool material; Ј=(NT+NM)Fa is the intensity of adhesion; NT, NM is, respectively, the number of active centres per unit of area of nominal contact Fa at thermal (NT) and mechanical (NM) activation; σa is the strength of bonds in adhesion centres; σp is the resistance of tool material to destruction.
Assisted synthesis of coatings when using technology has several advantages that are associated with mixing and alloying of deposited condensate by high-energy ions and are developed in the form of the following effects: • high entropic structures of increased hardness and heat resistance are formed at alloying of deposited condensate by various elements; • adhesion strength in the "substrate-coating" system increases significantly; • temperature of processes of the synthesis of coatings different in composition and structure decreases (up to 150-250°C), and that allows forming nano-dimensional grained structure (coagulation of grains is blocked) and significantly expands the range of materials, which may be coated.
It was found out that at the microhardness HV0.05 = 3.2 GPa, adhesion strength with the hard substrate Pcr = 140 N, the thickness of WRC of 3.9 μk, the grain size of 10-12 nm and thickness of subslayers of all three components (WC, IC, AC) of 20-25 nm obtained with UIMP = 30 kV, a tool, equipped with CP of T14K8 of TiN-TiCrAlN when turning steel 40X,provided maximum increase of wear resistance (up to 1.5-2 times) in comparison with the wear resistance of a tool of T14K8 with WRC of similar composition formed using of arc-PVD (fig.1).

On the surface of the Ni-Co-P coating one can observe the fine-grained structure with a high number of interfaces between nickel and cobalt grains which may participate in the HER or the OER (Fig. 2a).
The SEM observations of the surface of the Ni-P coating reveals the very fine-grained structure and at some places small pores are visible (Fig. 2c).

Thus the typical MIM production of high-strength Ni-based superalloy components entails a number of sequential, time-consuming and expensive manufacturing steps which hinder the overall advantages of the entire MIM manufacturing route.
The higher temperature and longer sintering time caused considerable grain growth in lot A samples, which turned out somewhat oversintered.
Since the assintered density of these samples was already fairly high (98,49 ± 0,10% TD), it's concluded the gain in density due to HIPping was not enough to compensate for reductions in those mechanical properties which might have been caused by grain growth during HIPing. 5 As-sintered parts: Sint'd & HIP'd parts: Sint'd & heat treated parts: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 364 ± 8 HV10N 355 ± 3 HV10N 382 ± 9 HV10N As-sintered dog-bones: Sint'd & HIP'd dog-bones: Sint'd & heat treated dog-bones: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 0,2%PS UTS Є 0,2%PS UTS Є 0,2%PS UTS Є [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] 800 1161 25
It's suggested HIP-induced grain growth caused these reductions despite the slight gain in density shown by the hot isostatically pressed parts. 5.