Search results

Grain size of powdery fraction was lower than 200 µm and was determined by the sieve analysis (Fig.6).
The cumulative wear in g/cm2 for a number of test cycles.
Each cycle represents a 500 m of path of friction (description in the Table No.1 above, circle – pure oil, square oil+coal, triangle oil+ore) Discussion In the case of presence a fraction with particle size of less than 200 μm for both material combination and corrosion state, the increasing intensity of wear was observed, which partially can be explained by the role the fine – grain particles as abrasive factor.
Generally at higher altitudes and farther away from the source will be observed increase in the share of the smallest grain fraction.

Thin layers of the powder (common grain size ranges from 25 to 200 m, depending on the material) deposited by the machine rake system are additionally pre-heated before melting.
This pre-heating helps to keep the elevated process temperature, to de-gas the powder grain surface and evaporate any adsorbed moisture, and to prevent the charged powder forming ‘clouds’ in the chamber.
Though significant number of different EBW and laser-based AM machines exists up to date, certain comparisons of critical parameters can be done.
It is mainly attributed to the fact that processing in EBM® is performed in deep vacuum, and majority of residual porosity there is attributed to the bubbles initially trapped in the powder grain.

Introduction Fluid mud is a special movement form for fine-grained cohesive sediment, and widespread phenomenon observed in muddy coast and/or estuary region.
The forming process of fluid mud can be described as follows: in salinity water, fine-grained cohesive sediment settlement is described no longer effectively by the single particle settlement theory but the flocculation theory.
Taking muddy coasts as example, during extreme weather days such as Typhoon, fine-grained cohesive sediment on the nearshore seabed can be re-suspended due to the fierce impact of wave and tide.
The medium grain size D50 of suspended sediments ranges from 0.002mm to 0.004mm based on historical field observations.
According to the relationship of sediment concentration and wave height indicated in Fig.3 and Fig.4, the corresponding wave height should be relatively larger, thus it can bring more energy to re-suspend the fine-grained cohesive siltation on seabed; (3) For the high rank of navigation channel such as 300,000DWT, the critical sediment concentration for fluid mud formation reduces to the range of 0.69-1.26kg/m3, and it is smaller due to the large water depth.

The tailings in some mines usually contain a large number of valuable elements which can be comprehensively recovered [1-2].
Part of chalcopyrite is immersed in gangues as micro-grained particles, which is difficult to liberate even if fine grinding, so both the recovery and the concentrate grade of copper will be affected.
It is filled with the gangue minerals in the fissures of part of broken pyrite, and a little amount of pyrite impregnates in gangues as micro-grained particles, and a little also disseminates in granular or irregular form of monomers.
Micro-grained magnetite can be seen to be immersed in the gangues, which is difficult to liberate from the gangues during grinding and would be partly lost in the tailings owing to its fine dissemination size and close combination with the gangues.
It is difficult to beneficiate the sulfur minerals as a result of high content of slimes, kaolinite etc. easy-to-slime minerals, and the micro-grained dissemination of part of the sulfur minerals (the occupation rate of pyrite in the fraction of less than 0.010mm reaches up to 11.41%).

The risk of undesirable spot welds led to the increasing of number of welds by approximately 20 %, which is time, energy and cost consumption [5].
The most important is the distribution of hard martensite grains in ferrite matrix.
The islands of martensite are dispersed around ferrite grains (amount of 10 to 30%).
Base metal of welded sample consists of a fine-grained structure with the ferritic matrix and island of the martensite.
The area of weld metal consists of coarse-grained structure of martensite as a consequence of rapid heating and subsequent cooling during the resistance welding process.

The results are found: there are a few of Ti (C, N) presented in the carbonitriding reaction production with theoretical amount of carbon at 1400℃; the content of Ti (C, N) increases with temperature; the carbonitriding reaction tends to finish at 1500℃; the average size of Ti(C,N) particles are 7.8452μm and the maximum is 21μm above 1600℃; the content of N in the Ti (C, N) decrease with temperature below 1400℃ and that of N increase and the change of C content is opposite above 1400℃; To increase appropriately carbon amount can promoto the carbonitride reaction which is benefit for the formation and grow of the Ti (C, N); when the amount of carbon beyond the theoretical value, the maximum and average size of grains obtained is smaller.
It shows that the bigger Ti(C,N) grains can be obtained and the high temperature is very important for the carbonitride treatment of the deep reduced slag to obtain Ti (C, N).
There is almost no melting phase in the sample and the main reaction may be solid-solid or solid-gas and the reaction not complete and a large number of free carbon residue in the product combining with Ti (C, N) into solid solution and so the ratio of C/N increase with temperature below 1400˚C.

Important parameters such as volume fraction, mean radius and number density of precipitates are experimentally determined and numerically simulated as a function of the heat treatment parameters time and temperature.
Introduction The term superalloy is generally used for a large number of different alloys.
The precipitation of a suitable quantity and size of coarse δ precipitates is used for controlling grain growth [3,4], whereas the precipitation of a large amount of fine-dispersed coherent γ' precipitates provides a large quantity of strengthening by precipitation hardening [5,6].
In Eq. 1, 0 represents the total number of potential nucleation sites.

Experimental results showed that the Vickers microhardness number have been increased to 66 by addition of 15% ZnO, which was double that of the matrix material.
Vickers microhardness number Composite (wt %) Hardness (VHN) AA7068 33 AA7068 + 5% ZnO 44 AA7068 + 10% ZnO 50 AA7068 + 15 % ZnO 66 Table 1 demonstrates the Vickers microhardness number of AA7068/ZnO composites.
The increased wear resistance and reduced volume loss can be attributed to the addition of hard ceramic particles, homogeneous distribution, grain size and sintering parameters [6].
Few large number of deep and shallow narrow plastic grooves were present paralleling to the sliding direction which is due to intensive material removal which is the characteristic of abrasive wear [5,12,17].

Results and Discussion SEM image of the ceramic surface is shown in Fig.1, show- ing a typical microstructure of electronic ceramics with homogeneously distributing grains in diameter of about 8 um.
Fig. 5 Bad percentage (left) and voltage distribution (right) of capacitors after the thermal shock Table 1 Insulation resistance and bad rate of voltage withstanding after damp heat Insulated resistance after damp heat Serial number Epoxy resin (g) / curing agent (g) Curing temperature / time R (average) > 10GΩ Bad rate of voltage resistance A 100 / 27 365 GΩ OK 0 % B 100 / 29 195 GΩ OK 0 % C 100 / 31 91 GΩ OK 0 % D 100 / 37 120 ºC / 1 h +130 ºC / 1 h. 50 GΩ OK 0 % Table 2 Bad rate of voltage withstanding of endurance with DC 10 kV at 100ºC for 500 h Serial number Epoxy resin (g) / curing agent (g) Curing temperature and time Bad rate of voltage withstanding A 100 / 26.8 0% B 100 / 29.4 0% C 100 / 31 0% D 100 / 37 120 ºC /1 h+130 ºC /3 h. 0%

But Ag prepared by solvated metal atom impregnation and functional ion pre-adsorption method can avoid some process such as drying, calcinations and high temperature reduction and so on Consequently, Ag has the properties of smaller average grain diameter, larger specific surface area and higher electrocatalytic activity in Ag/C catalysts prepared by solvated metal atom impregnation and functional ion pre-adsorption method [5, 6].
Table 1 The fabrication of Ag/C catalysts Number Mass ratio （PVP/ AgNO3） Concentration of AgNO3（mol/L） Concentration of NaBH4（mol/L） Ag/C catalysts（Ag%） 1 2︰1 0.01 0.01 20 2 2︰1 0.02 0.01 20 3 5︰1 0.01 0.01 20 4 10︰1 0.01 0.01 10 5 10︰1 0.02 0.01 20 3.2 SEM test Fig1-fig5 show the images of Ag/C catalysts obtained by XL30 ESEMFEG(SEM).
Table2 The results of XRD test of Ag/C catalysts Number Mass ratio （PVP/AgNO3） Concentration of AgNO3（mol/L） Concentration of NaBH4（mol/L） Ag/C catalysts(%) Particle size of Ag(nm) 1 2：1 0.01 0.01 20 38.2 2 2：1 0.02 0.01 20 76.6 3 5：1 0.01 0.01 20 33.4 4 10：1 0.01 0.01 10 23.6 5 10：1 0.01 0.01 20 25.1 3.4 polarizations curves Fig6 shows that the polorization curves of oxygen reduction on the electrode with Ag/C catalysts.As shown in Fig6, the electrocatalytic activity of Ag/C catalysts prepared by the polymeric complex protection for Ag(I) enhanced with increasing concentration of AgNO3, the electrocatalytic activity decreased with increasing concentration of AgNO3 at a certain mass ratio of PVP/AgNO3 and the electrocatalytic activity strengthened with increasing concentration of Ag at a certain mass ratio of PVP/AgNO3 and concentration of AgNO3.