RATE OF DECOMPOSITION OF KYANITE AT VARIOUS TEMPERATURES*

Steels treated through carburizing thermochemical treatment and quenching and tempering thermal treatment are broadly used in components that need to have hardness and superficial mechanical resistance together with good toughness in the core of the component. Additionally, it is possible to produce surface compressive residual stresses that normally improve fatigue resistance. Relatively unknown, the intensive quenching thermal treatment is a method that presents some advantages, one of them being the possibility of avoiding cracking by distortion due to extreme cooling. Other advantages are the increase in mechanical resistance, the use of shorter carburizing cycles, improvement of fatigue performance, among others. Once the cooling rate is high, low carbon steels can be used instead of low alloy steel such as AISI 8620. This way, it is possible to use less costly steel and to obtain the advantages of intensive quenching. The present work aims to compare samples carburized during 6 hours at a temperature of 920oC and carbon potential of 0,9% both for AISI 1020 and AISI 8620 samples, through mechanical and metallurgical analyses, being the principal the production of Wohler curves together with fractographic analysis in low magnifying glass and scanning electron microscope. Results pointed out that the AISI 1020 steel presented grain size which is three times bigger than AISI 8620 steel grain size. The effect of optimizing intensive quenching when applied to AISI 1020 steel is practically covered by the fact that AISI 8620 steel presents a more refi ned structure, with smaller grain size comparatively and therefore better mechanical properties. This way, intensive quenching treatment can provide superior performance to non-alloy steels relatively to alloy steels only if grain size is equal or inferior. Key words: carburizing, intensive quenching, fatigue.

Reaction Sintering of Kyanite and Alumina to Form Mullite Composites

Grain size versus standard deviation was applied to extract sensitive grain size from the grain size distribution data of the Holocene KE peat deposit of the Gonghe Basin,northeastern Qinghai-Tibetan Plateau.We found that the sensitive grain size component of 63~252 μm(63~112 μm and112~252 μm)can reflect the intensity variation of the regional winter monsoon,upon which we reconstructed the history of the regional winter monsoonal evolution.Our results suggest that the intensity of winter monsoon declined in the period of 10.0~8.5 cal.kaBP,and obviously increased in 8.5~7.1 cal.kaBP.The weakest winter monsoon emerged in 7.1~ 3.8 cal.kaBP,and it became stronger in the period between 3.8 cal.kaBP and 0.5 cal.kaBP.Afterwards,the winter monsoon rapidly weakened.Comparative study demonstrates that the evolution of regional winter monsoon is correlated well with the climatic change records of the Qinghai-Tibetan Plateau and the marginal monsoonal zone and monsoonal zone in eastern China from different research sources.We also found seven phases of the stronger winter monsoon,which are apparently coincident with the cold events found in the polar ice core and North Atlantic Ocean,probably indicating the inherent relationship of the dynamic mechanism between the regional and the global climatic changes.

The Nile Delta coast is a dynamic sedimentary environment experiencing erosion, transport and re-deposition of sand along the coast. The aim of this study was to investigate the effectiveness of using an integrated approach of natural radioactivity of coastal sediments, heavy mineral distribution and grain size information to differentiate between the eroding and accreting areas of the Nile Delta coast. Also, it is to investigate the relationship between grain size and heavy mineral distributions of these sediments on the spatial distribution of the coastal radioactive materials. The relatively higher profile averages of 226Ra, 214Pb, 214Bi and 210Pb (as 238U series) were 104.37±84.66, 45.60±37.83, 38.43±32.49 and 35.69±24.86 Bq/kg, respectively and228Ra and 212Pb (as 232Th series) were 54.26±56.66 and 42.18±44.66 Bq/kg, respectively. The highest average value of 40K concentration (404.49±125.81 Bq/kg) was detected in the profile located at 2000.1 m west of Rashid estuary. Microscopic study revealed that the more dominant heavy minerals assemblages consisted of Opaques, Hornblende, Augite, Epidote, Biotite and Chlorite. Also, minor amounts of Garnet, Zircon, Rutile, Tourmaline, Kyanite and Monazite have been identified. Relatively high concentrations of 238U and 232Th series members were found in coincident at sites having higher heavy minerals percentages and detected at erosional beach than the accretion one. Coincidence was recognized between the average concentrations of40K and the percentages of the light minerals collected at 100 m distances of the profiles under investigation. Key words: Nile Delta, beach erosion, beach accretion, natural radioactivity, heavy minerals.

STRUCTURAL AND MORPHOLOGICAL CHARACTERISTICS OF PLASMA SPRAYED TiO 2 -COATINGS. TiO 2 thin layers have been deposited on glass substrates using Plasma Spray technique. The TiO 2 starting powders are a laboratory grade commercial powders. Before spraying, to check the availability of the basic material for Plasma Spray technique, a series of characterization was conducted. The TiO 2 starting powders were identified its particle size using Particle Size Analyzer (PSA) resulting diameter at 90% was 42.72 µ m. X-Ray Diffractometer (XRD) measurement was done to identify the peaks of the basic material elements using K α radiation at wavelength 1.5406 A resulted TiO 2 of Anatase structure. Spray dry process was then conducted in order to get circular and free flowing particles for feedstock of plasma spray system. Distribution of particles showed a dominat of 20 µ m diameter-free flowing particle. Plasma Spray process of TiO 2 powder furthermore was conducted on slide glass microscope under several parameter conditions such as power, flame-substrate distance and preheating treatment variation. The TiO 2 /glass coatings with variation of flame-substrate distance (10 and 12 cm) resulted in 5.806 µ m and 4.913 µ m layer thickness with grain size in the range of 0.8-2 mand 1-2.8 µ m, respectively. XRD diffractogram results revealed that the TiO 2 layer are dominat in rutile phase but at a little higher of plasma power, low anatase phase existed. The preheated-plasma sprayed TiO 2 coatings were visibly difussed into the glass substrate and resulted in dominat rutile phase (at 2 cycles preheating) but not existed in a longer preheating time (4 cycles preheating treatment).

1 core(132 cm long and 44 samples) and 50 bottom sediments samples were collected in the offshore area on the north side of the Huanghua Harbor,and grain size analysis was carried out with Mastersizer2000.Results indicate that there are three types of bottom sediments,namely sandy silt,silt and clayey silt,in the area.Sandy silt is distributed in the subtidal zone on the north side of the harbor,silt mainly in the offshore area-2m~-5m in water depth at Daxinpu and sampling site 13,and clayey silt in the other area.The Harbor has cut off the coastal current,and changed it to the direction along the dam of the Harbor,that caused the currents-carried sediments deposited on the tidal flat and the area near the dam.As an evidence of the abandoned deltaic coast,sandy silt near the Harbor suggests that the impact of the construction of the Harbor is limited to the tidal flat and its nearshore area.According to the vertical grain size distribution pattern of the sediments,the Hole HHG2 can be divided into four segments from bottom to top:(1) the segment with slight fluctuation of coarse-fine grains in 132~100.5 cm,(2) the segment slowly coarsening up in 100.5~56 cm,(3) the segment with rapidly coarse-fine fluctuation caused by episodic events in 56~16 cm,and(4) the segment rapidly coarsening up in 16~0 cm.Furthermore,the forth segment of 16~0 cm is well correlated to the period from 1917 up to present defined by 137Cs tracing and dating.During the period,the fluvial process was weakened due to the shift of the Yellow River eastward,and the enhancement of marine process by sea level rise.

Amongst the thin-film based approaches for photovoltaics, which aim to combine high conversion efficiencies (> 10%) and low cost manufacturing (<1$/Wp), poly-crystalline silicon (poly-Si) based solar cells (<10 µm thick) are nowadays considered a promising candidate. Poly-Si couples the high quality crystalline Si technology with the potential for large area and low-cost thin film manufacturing. One of the most followed approaches is the development of poly- Si on inexpensive (e.g. glass) substrates upon solid-phase crystallization (SPC), i.e. an annealing procedure under a controlled temperature ramp up to 600-650 °C, of plasma- deposited amorphous silicon (a-Si:H) films. Here the challenge is the development of large (in the range of few µm) grain poly-Si and large area, high growth rate a-Si:H films have generated in the recent years several (fundamental) research questions. Among these, the impact of the a-Si:H microstructure on the crystallization kinetics (incubation-nucleation-grain development) represents the key towards large grain poly-Si and process up-scaling. The approach chosen in this Ph.D. project initiates from the development of state-of-the art poly-Si layers characterized by grain sizes developing up to a 1 µm in diameter, as obtained upon SPC of expanding thermal plasma deposited a-Si:H layers [1]. Furthermore, a selected experimental approach based on an extensive use of in situ and ex situ surface and bulk film diagnostics is applied with the purpose of disclosing the impact of the a-Si:H film properties on the crystallization kinetics. In particular, a-Si:H bulk parameters such as the hydrogen content and microstructure parameters (hydrogen distribution in several SiHx configurations, medium range order) are studied in depth [2-3]. In detail, larger grains are found to be promoted by an increase in the a-Si:H microstructure parameter R* [2]. R* represents the order (low R*)/disorder (high R*) in the matrix according to the Si-H bond distribution in mono-/di-vacancies (–low stretching mode-LSM) and nano-sized voids (–high stretching mode-HSM), and it is quantified by the integrated IR absorption band ratio IHSM/ (ILSM+IHSM). Furthermore, the incubation time towards nuclei formation appears to be not only controlled by the medium range order in the a-Si:H films, as previously reported in literature, but also by the density of nano-sized voids which undergo a faster hydrogen out-diffusion and chemical bond rearrangement towards a higher medium range order and more ordered microstructure. Next to the insight into the impact of the a-Si:H properties on the crystallization kinetics, an in-depth study is also devoted to the control of the a-Si:H properties by means of a proper tuning of film growth- related parameters such as the ion flux and energy involved during the plasma deposition of thin a-Si:H layers [4]. In view of the manufacturing challenges of high throughput, the expanding thermal plasma approach is further explored [5] for the deposition of high growth rate a-Si:H films, in the range of 11- 58 nm/s. Poly-Si layers characterized by large grains (~1.5 µm) were obtained from disordered a-Si:H films deposited at 11- 25 nm/s. The study confirmed the role of the medium range order and the R* parameter in affecting the crystallization kinetics of a-Si:H, i.e. the incubation time and the grain size development, respectively. The present thesis addresses the results of the research efforts towards high conversion efficiency, high throughput thin-?lm poly-Si solar cells. It addresses a significant contribution to the insight on the SPC kinetics, the impact of a-Si:H microstructure on the incubation step and grain development and demonstrates the potential for large grain (~1.5 µm), high growth rate (~25 nm/s) poly-Si from SPC of ETP deposited a-Si:H films.

Grain-size analysis is carried out for the 95surface sediment samples from the southwestern part of the South China Sea(3°56′~11°53′N,108°30′~113°47′E),where clayey silt and silty clay dominate,with sand and silty sand only occurred in the most southwestern shallow part.There shows a trend of decreasing grain-size,increasing sorting and decreasing skewness from the shallow water to deeper water.The Kriging method was employed to insert data of the grain-size parameters(mean grain-size,sorting coefficient and skewness),and then the trend analysis was carried out for the interpolated data using the GSTA program.It is revealed that the seabed topography plays a key role in the sediment transport.There is a topographic high in the area including the Guang-ya submarine plateau,the Nan-wei-tan plateau,and the Yong-shu-bei submarine plateau.To the north of the high,sediments from the western South China Sea continental shelf are transported into the Southwest Basin of South China Sea;to the south of the boundary,however,materials from the Sunda shelf and the Kalimantan Island are transported into the Nan-wei-xi and Bei-kang slope basin passing by the shelf break.The episodic sedimentary events,such as the turbidity current,also have significant impacts on the grain-size distribution pattern.The aggregation of the components8μm should not be ignored.Further researches are required for details.

Solid-phase crystallisation (SPC) of hydrogenated (H + ) and dehydrogenated (H - ) Si thin films on glass deposited by electron-beam (e-beam) evaporation (EVA) and plasma-enhanced chemical vapor deposition (PECVD) is compared. Four independent film characterisation methods, optical transmission microscopy (OTM), UV reflectance spectroscopy (UV-R), X-ray diffraction (XRD) and Raman spectroscopy, reveal that for the SPC process at 600oC the evaporated films have similar incubation and nucleation times as the PECVD films but the number of initial crystal grains is less and their growth rate is faster in the evaporated films. The scanning electron microscopy (SEM) images of fully crystallised polycrystalline Si film (poly-Si) samples after Secco etching show that the average grain size is larger in the evaporated film. The resulting quality of evaporated poly-Si appears to be at least as good as the quality of poly-Si made by PECVD promising similar cell efficiencies. Hydrogen is not responsible for the observed differences between SPC of the films from two different deposition methods. Keywords: 1. Poly-Si 1. Solid Phase Crystallisation 2. Si e-beam evaporation 3. a-Si:H PECVD

Introduction: Recently, air pollution due to the occurrence of dust storms is one of the worst environmental problems in Western and Southwestern Iran, especially the Khuzestan Province (12, 13). According to the reports of the Meteorological Organization of Iran the average number of dusty days in the cities of Ahvaz and Abadan in the Khuzestan Province reaches 68 and 76 days each year, respectively (6). Previous studies have shown that the yearly damage costs of wind erosion and occurrence of dust storms in the Khuzestan Province reach about 30 Billion Rials (5). However, very few studies have been conducted on the characterization of dust particles and also the identification of their origins in Iran, especially the Khuzestan Province. Hojati et al. (10) reported that dust deposition rate, mean particle diameter, and concentration of soluble ions in samples taken from Isfahan and Chaharmahal and Bakhtiari Province decrease with altitude, with a significantly lower gradient in periods with dust storms. They reported three factors that control the rate and characteristics of dust deposited across the study transect: 1) climatic conditions at the deposition sites, 2) distance from the dust source, and 3) differences between local and transboundary sources of dust.Therefore, this study was conducted to investigate the effects of dust storms on deposition rate, mineralogy and size distribution patterns of dust particles from twelve localities around the Houralazim lagoon. Materials and Methods: Dust samples were collected monthly during a 6 month experiment from August 2011 to February 2012. In order to differentiate between the contribution of dust production by local soils and other sources, surface soils were also sampled from the vicinity of the dust sampling sites. The collection trays were made of a glass surface (100 × 100 cm) covered with a 2 mm-sized PVC mesh on the top to form a rough area for trapping the saltating particles (Fig. 2). Dust samples were collected by scraping materials adhered to the glass trays using a spatula. All the trays were wet cleaned before the next collection. The collected dust and soil samples were examined for their grain size distribution using a Malvern Hydro 2000g laser particle size analyzer, as well as their mineral compositions by a Philips PW1840 X-ray diffractometer and a LEO 906 E transmission electron microscope (TEM). Results and Discussion: The results showed that wind speed and direction patterns during the periods with dust storms and those without dust storms were different. Accordingly, in periods with dust storms (3, 5 and 6) the contribution of winds with speeds greater than 11.1 m/sec, especially from the Northwest direction, increased when compared with those from the periods without dust storms (1, 2 and 4). Besides, the direction of prevailing winds in periods without dust storms were mainly from the West and the Northwest. However, in periods with dust storms East-directed winds were also observed (Fig. 3). These show that the source areas of dust particles in these periods are probably different. The results also illustrated that the average amount of deposited particles in the periods with dust storms (12.5 g m-2 month-1) was considerably more than that of the periods without dust storms (7.5 g m-2 month-1) (Figs. 4 and 5). The difference in dust deposition rate between periods having dust storms and those without dust storms seems to be due to dust input from a source outside the study area. Particle size distribution analysis showed that dust particles collected from the study area in both periods (with and without dust storms) are mainly silt-sized particles. This fraction contributes to 60 to 76 % of the particles collected from periods without dust storms and 66 to 82 % of particles affected by dust storms (Table 2). The results also imply that in both periods (with and without dust storms), dust particles collected from the study area had a bimodal distribution pattern which suggests mixing of settled particles from different sources and/or deposition processes (Fig. 6). Mineralogical composition of dust particles were collected from both periods (with and without dust storms) and those from the soils contained quartz, calcite, feldspar, halite, dolomite and palygorskite (Figs. 7 and 8). Moreover, the TEM images of dust particles collected in periods with dust storms showed higher amounts of palygorskite than in periods without dust storms (Fig. 9). Conclusion: The similarity in the physical properties of local soils and deposited particles of the periods with and without dust storms implies that the contribution of local soils and sediments in producing dust particles is high. However, it seems that in periods with dust storms the contribution of a transboundary origin such as Iraqi arid lands in producing dust particles increases.

Grain size and heavy mineral analyses of 6 cliff, 12 beach, and 44 marine sediment and rock samples from Bolmas Bay and its surrounding drainage area were done as part of a long term study of sediment transport on the continental shelf off Central California Sediments in the bay are predominately very fine sands Some samples, particularly adjacent to Duxbury Reef on the west, have a coarse sand to pebble component The primary mode of the marine samples is in the range 088 to 125 mm, whereas, the primary mode for beach material is from 175 to 25 mm The range of median diameters of the marine samples is from 07 to 14 mm The median diameters show a trend of decreasing grain size seaward parallel to the depth contours except opposite the entrance to Bolmas Lagoon where a tongue of relatively coarser material cuts across the depth contours The range of other statistical parameters are (1) sorting coefficient 1 10 to 1 41, (2) skewness 0 83 to 1 18, and (3) kurtosis 0 15 to 0 32 Our sediment studies indicate (1) The heavy mineral assemblage is predominantly green hornblende with secondary amounts of hypersthene and augite Glaucophane and jadeite occur in locally high concentrations near shore (2) The pattern of distribution of the heavy minerals shows (a) a tongue of high concentrations of minerals with a granitic source extending northwest from the San Francisco Bar, (b) flanked on the north and northeast by increasing landward concentrations of Franciscan metamorphic minerals (3) The major source of heavy minerals is the San Francisco Bar Secondary contributions come from Bolmas Lagoon and the adjacent cliffs (4) The circulation in the Bay is primarily counterclockwise, produced by a combination of wave refraction around Duxbury Reef and the tidal Coast Eddy Current The tidal influence, however, of Bolmas Lagoon is restricted to about one mile from the lagoon mouth.

For the first time, an unusual assemblage of talc-phengite-chlorite-K-feldspar was found in quartz schists from the Sanandaj-Sirjan zone in the Nahavand area in western Iran. The talc-bearing quartz schists occur as small bodies or lenses within pelitic schist layers and contain talc, phengite, chlorite, K-feldspar and quartz as major mineral constituents with subordinate amounts of calcite and graphite. Textural analysis revealed that talc, phengite, chlorite and K-feldspar are in sharp contact and no reaction rims between them were observed. Constructed petrogenetic gird in the K 2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH) model system containing talc, phengite, chlorite, K-feldspar, phlogopite and kyanite with excess quartz and H 2O shows that divariant assemblage of talcphengite- chlorite-K-feldspar is stable over a wide P-T range defined by the following two univariant reactions: phengite + talc + quartz = chlorite + K-feldspar + kyanite + H 2O and chlorite + phlogopite + quartz = talc + phengite + K-feldspar + H 2O. Constructed Al2O3-KAlO2-MgO+FeO (AKM) compatibility diagrams predict that phengite (X Ph = 0.280, YPh = 0.860), chlorite (XChl = 0.570, YChl = 0.640), talc (XTlc = 0.160, YTlc = 0.02) and Kfeldspar are stable at P = 11 kbar and T = 400°C. This relatively high-pressure assemblage could be formed during the subduction of the Neo-Tethys oceanic plate under Iranian microcontinent.

Waste glass is often the trash unused and potentially damaging to the environment because it is difficultto decompose. Though glass waste has the potential to be used, one of them as a substitute for cement inconcrete solid brick. The purpose of this study was to determine how much influence the addition of glasspowder waste of compressive strength of concrete solid brick. Manufacture of solid concrete brick made fromwaste fine aggregate, cement PC type I, and glass powder from waste glass bottles. Test object of research ismade with a composition ratio of cement, fine aggregate and water with glass powder 4 substitution treatmentwere 0%, 10%, 20%, and 30% by weight of cement. Compressive strength testing is done on day 7,14, 21 and28. From the test results obtained optimum compressive strength value contained in glass powder ratiovariation of 10% of the cement with the compressive strength obtained at 73.33 Kg / cm2 and included intothe Tertiary quality II. This shows the glass powder can be used as an additive in the manufacture of solidconcrete brick so that it can be used as an alternative to environmentally friendly construction materials.

The aim of this study is to assess the effect of additional curing procedures on the flexural strength and modulus of elasticity of indirect and direct composite materials. Twenty-four rectangular prism-shaped 2 mm x 2 mm x 25 mm samples of Belleglass, Premisa (Kerr), Adoro and Heliomolar (Ivoclar Vivadent) were prepared. Each composite was packed in an ad-hoc stainless steel device with a TeflonR instrument. A mylar strip and a glass slab were placed on top to obtain a flat surface. Polymerization was activated for 20 seconds with a halogen unit (Astralis 10, Ivoclar - Vivadent) with soft start regime and an output with a 350 to 1200 mw/cm2 range at four different points according to the diameter of the end of the guide. The specimens obtained were then randomly divided into two different groups: with and without additional treatment. In the group with additional treatment, the samples adorro were submitted to 25 minutes in Lumamat 100 (Ivoclar Vivadent) and the rest to 20 minutes in BelleGlass HP (Kerr). After the curing procedures, all samples were treated with sandpapers of decreasing grain size under water flow, and stored in distilled water for 24 h. Flexural strength was measured according to the ISO 404920 recommendations and elastic modulus was determined following the procedures of ANSI/ADA standard No. 27. Statistical differences were found among the different materials and curing procedures employed (P<0.01). The elastic modulus was significantly higher after the additional curing treatment for all materials except Premisa. Further work is needed to determine the association between the actual monomers present in the matrix and the effect of additional curing processes on the mechanical properties of both direct and indirect composites, and its clinical relevance.

The current paper presents a novel experimental method which is able to capture the effects of suffusion by substitution of the fines in a sample by salt of a similar grain size. The setup is tailored to optically capture the change in soil structure behind a glass window in a plane strain strongbox using a digital camera. Subsequently, digital image correlation techniques have been used to quantify the structural change. The first model test shows promosing insight in the pseudo suffusion mechanism. The test setup therefore offers a valuable addition to permeameter tests.