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A few years back, a number of studies were performed in synthesizing mullite-based ceramics using untreated RHA were very little [10].
Besides, it was recognized that the morphology of the crystallites differed according to primary (elongated grains) and secondary (equaixed grains) [5].
At 1300 °C (Fig. 3(b)), a constant multi-crystallization happening in the sintered samples and an increment in the grain size of mullite crystals with the elimination of average pore distribution.
Primary mullite started to form at 1300 °C (elongated grains) while secondary mullite crystals (equaixed grains) were formed at ≥ 1400 °C.

A number of studies have therefore been performed to investigate the deformation mechanisms and the influencing factors, including the grain size, chemical composition and stacking fault energy (SFE), mostly by using monotonic tensile test [3-5].
Ueji et al. [5] reported that mechanical twinning was significantly suppressed by grain size.
By investigating the effects of grain size and stress ratio on the FCG of Fe-22Mn-0.6C steel in a solution state [7], it is found that the coarse-grained TWIP steel exhibited an enhanced FCG resistance, as compared with the fine-grained TWIP steel, and a decreased stress ratio improves the crack growth resistance.

Plastic deformation creates orientation differences in grains of originally uniform orientation.
Introduction Plastic deformation introduces orientation differences within grains of originally homogeneous orientation leading to a subdivision of original grains by deformation-induced boundaries.
In general, the shape of the distribution function depends on the number of independent rotation axes [9].

The major wear mechanism of the composites was adhesive wear and abrasive grain wear.
Now a large number of POM composites applied in tribological field contain polytetrafluoroethylene (PTFE), MoS2, synthetic fibers, which are used as internal lubricants or reinforcements[4-6].
The two characters may indicate the major wear mechanism of the composites filled with untreated SF and 12.5% NaOH treated SF is adhesive wear and abrasive grain wear.
The major wear mechanism of the composites is adhesive wear and abrasive grain wear.

Nova 59072-970 Natal - RN, Brazil carlson@ufrnet.br Keywords: spray drying, ammonium niobium oxalate, precursor ABSTRACT The main purpose of this paper is to present a spray dryer device developed to synthesize ammonium niobium-oxalate precursor powder with controlled grain size.
Furthermore, the large number of parameters as well as the lack of information available on the literature on this subject were the main difficulties.
P, Silva A.G.P, Souza C.P., A low temperature synthesized NbC as grain growth Inhibitor for WC-Co Composites, Materials Science and Engineering A, 293, (2000), 242-246. 2 - Ciaravino C, Medeiros F.F.P, Souza C.P, Satre P, Roubin M, Gomes U.
Elaboration of mixed tantalum-niobium carbides elaborated from oxalic complex (NH4)(Ta1-xNbx)O(C2O4).nH2O from tantalite mineral (Fe,Mn)(Ta1xNbx)2O6. 14th International Congress of Chemical and Process Engineering 27-31 august, (2000), Praha, Czech Republic. 3 - Clar, E.; Doctorate Thesis: Obtention et propriétés de carbures métalliques simples et mixtes à grain fin, Faculty of Sciences at the Lyon University, (1964), Lyon, France. 4 - Toth, L.

The microstructures of Al/AlTi and Al/Al-Si coating films have very fine grain size.
However, conventional coating processes generally have following major technical problems; low adhesive strength at the interface, the difficulty of controlling structure and grain size in coating film especially in case of high deposition rate methods and the difficulty to suppress defects such as voids, cracks and columnar boundaries [1].
The gas flow is accelerated to supersonic velocity (Mach number 3.6) by a specially designed supersonic nozzle joined to the tip of the transfer pipe.
In the figure, some typical grains of Al or Si are indicated.

In Fig. 7(b), the grain structure is compact, and clear grain boundaries can be observed with an average grain size of 2.5–3um.
The same conditions, with the Cu doped increase samples have been in sintering later, grain have already grown up, grain boundary part ablation, section a transgranular fracture morphology In the same sintering a b c d e Fig. 7.
conditions, the grain structure is already quite dense for the specimens of x .The grains are relatively close and uniform, and grain boundaries are clearly visible with an average grain size about 3–6 um.
The neutrality condition is described as In another hand Ca'Pr, Nd'Pr formed by a large number of oxygen vacancies and Cr3+ Cr6+ to change to get the electronic compensation.
In the low oxygen partial pressure conditions such as in H2, the material form a large number of oxygen vacancies because of some oxygen ions lost ,in another meaning in a reducing atmosphere, oxygen is converted to a dot matrix with two positive charges, while the oxygen vacancies consume electron hole 2, so that PNCC material than the conductivity in a hydrogen atmosphere, a sharp decline in the air.Cu replace part of Cr it can effective improve PNCC sintering activity. 3.4 Thermal expansion coefficient Fig. 11.

Comparing fusion zone (Fig.3a) and surface area (Fig. 2c), it can be found that the number and volume content of TiC particles in the fusion zone of the coating at 250A is higher than the number and volume content of TiC particles in the fusion zone at 350A of the coating.
It can be observed that with the increase of the number of overlapping coating layers, the number of reacted TiCs in the coating increases, the size increases, and the distribution of particles to dendritic aggregation changes.
As mentioned earlier, due to the large dilution rate, the number of TiCs reacted and synthesized in the coating is small, and they are mostly distributed in austenite and eutectic phase (Cr,Fe)7C3 grains, and a small amount of particles are also aggregated.
Only a small number of areas have formed a melting pool and coating.
Grain-abrasion Performance and Mechanism of High-chromium Iron-base Coating Prepared by Plasma Cladding, Reseach and exploration in laboratory. 28(2009)24-26

The formation of this phase can be fundamentally studied the number of mass fractions of formed phases and structure crystallography using X-ray diffraction facilities and is supported by spectroscopy facilities and their magnetic properties.
So it was concluded that the presence of Pr was able to withstand the growth of grain, causing the anisotropic magnetocrystalline field to increase.
Grain morphology was observed with an optical microscope (MO) Hitachi TM-3000.
The qualitative and quantitative analysis refers to the Crystallography Open Database with card numbers (COD: 1008718), (COD: 5000217), and (COD: 180909) for the Nd2Fe14B neodymium iron boron phase, iron Fe, and praseodymium Pr.
The presence of Pr can hold grain growth so able to increase its anisotropic magneto-crystalline field.

The presence of respective atomic concentration gradient of Ti, B, C, Fe and the others between the ceramic and the steel reasoned for continuously-graded interfacial microstructure in which the TiB2 and TiC phases transform sub-micrometer, micro-nanometer grains from the micrometer ones.
Meanwhile, XRD, FESEM and EDS results at the intermediate of near steel substrate showed that a number of sub-micrometer or micro-nanometer particles of nonstoichiometric TiC1-x were embedded in the Fe-based intermediate, as shown in Figs. 5 and 6.
As a result, there are a number of sub-micrometer or micro-nanometer particles of nonstoichiometric TiC1-x embedded in Fe-based intermediate, as shown in Fig. 5 and Fig. 6.
Meanwhile, a number of sub-micrometer or micro-nanometer particles of nonstoichiometric TiC1-x were embedded in the Fe-based intermediate nearby the steel substrate.
In terms of composite process during combustion synthesis in high gravity field, liquid fusion followed by atomic interdiffusion between the ceramic and the steel results in the formation of spatial span-scale graded microstructure from the ceramic to the steel, in other word, the presence of respective atomic concentration gradient of Ti, B, C, Fe and the others between the ceramic and the steel reasons for continuously-graded interfacial microstructure in which the TiB2 and TiC phases transform sub-micrometer, micro-nanometer grains from the micrometer ones.