Chemical Enigineering

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al-and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, the additions of ashes up to 15% wt. resulted in only slight deterioration of the wear performance of composites.

Dry sliding wear behaviour of cenosphere reinforced aluminum syntactic foam having density of 1.9 g/cc (around 30% porosity) has been studied using a pin-on-disc apparatus at load range of 1-5 kg and sliding velocity of 2-4 m/s. Coefficient of friction and wear rate of the syntactic foam has been compared with that of 10 wt% SiC reinforced aluminum composite. Scanning electron microscope (SEM) is used to characterize the microstructure and the worn surface for examining the wear mechanism. The craters on the specimen surface due to presence of cenosphere play important role in the wear process.

In this paper, waste glass powder (GP) is selected as a sustainable abrasive to replace pure silica minerals. XRF analysis to determine the content of glass waste. Composite specimens have volume fraction ratios of 0%, 2%, and 4% GP evaluated with TGA, Pin on Disc friction test, and Hardness Rockwell type R. Scanning electron micrograph (SEM) observe the formation of abrasion and surface wear of the specimen. The results of the X-ray fluorescence (XRF) glass powder waste obtained that the main content of silicon dioxide (SiO2) was 65.58%. Thermogravimetry (TG) showed that the thermal resistance of the composite from the addition of glass powder increased. Glass powder as an abrasive shown that increase the coefficient of friction brake friction materials. The presence of glass powder increases the hardness of the composite, and the coefficient of wear rate of the composite decreases.

Polish bituminous (PB) and South African (SA) coal fly ash (FA) samples, derived from pilot-scale circulated fluidized bed (CFB) combustion facilities, were utilized as raw materials for the synthesis of zeolitic products. The two FAs underwent a hydrothermal activation with 1M NaOH solution. Two different FA/NaOH solution/ratios (50, 100g/L) were applied for each sample and several zeolitic materials were formed. The experimental products were characterized by means of X-ray diffraction (XRD) and energy dispersive X-ray coupled-scanning electron microscope (EDX/SEM), while X-ray fluorescence (XRF) was applied for the determination of their chemical composition. The zeolitic products were also evaluated in terms of their cation exchange capacity (CEC), specific surface area (SSA), specific gravity (SG), particle size distribution (PSD), pH and the range of their micro- and macroporosity. Afterwards the hybrid materials were tested for their ability of adsorbing Cr, Pb, Ni, Cu, Cd an...

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al-and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, the additions of ashes up to 15% wt. resulted in only slight deterioration of the wear performance of composites.

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al-and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, the additions of ashes up to 15% wt. resulted in only slight deterioration of the wear performance of composites.

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al-and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt.% ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a ...

Focus of the study has been placed on the effect of graphite content on tribological behavior of a Cu-Fe-C based friction material sliding against FC30 cast iron. Experimental results indicated that, after sintering in air, the densities of Cu-Fe-C specimens decreased, oxygen contents increased, and essentially all original metallic constituents turned into oxides. As graphite content increased, the amounts of Fe 2 O 3 , Cu 2 O and Cu-Sn decreased, while CuO and FeSn 2 contents increased. The friction coefficient profiles of Cu-10%Steel wool-10%Al-10%Al 2 O 3-10%Sn (vol%) material (C0) and Cu-10%Steel wool-10%C-10%Al-10%Al 2 O 3-10%Sn (vol%) material (C10) are almost identical. After sliding for a few minutes, their friction coefficients start to decay. The friction coefficient of Cu-10%Steel wool-20%C-10%Al-10%Al 2 O 3-10%Sn (vol%) material (C20) maintained to be high and stable throughout tests. The mass loss of C20 was larger than that of C0 or C10. The mass loss of FC30 sliding against C20 was smaller than that of FC30 sliding against C0 or C10. While both particulate and film types of debris were observed on each Cu-Fe-C specimen, more particulate debris was observed on C0 and C10 than on C20 surface. Chemical analysis of worn surfaces indicated that Fe was dominant on C0 and C10 surfaces, while large amounts of Fe and Cu were detected on the worn surfaces of both C20 and FC30.

Potential of widespread industrial applications of magnesium has been realized in recent years. A variety of magnesium alloy matrix composites are now being studied for mechanical properties. Since magnesium is the lightest structural metal, it can replace aluminum in existing applications for further weight savings. This review presents an overview of hollow particle filled magnesium matrix syntactic composite foams. Fly ash cenospheres are the most commonly used hollow particles for such applications. Fly ash cenospheres primarily have alumino-silicate composition and contain a large number of trace elements, which makes it challenging to study the interfacial reactions and microstructure in these composites. Microstructures of commonly studied AZ and ZC series magnesium alloys and their syntactic foams are discussed. Although only a few studies are available on these materials because of the nascent stage of this field, a comparison with similar aluminum matrix syntactic foams has provided insight into the properties and weight saving potential of magnesium matrix composites. Analysis shows that the magnesium matrix syntactic foams have higher yield strength at the same level of density compared to most other metal matrix syntactic foams. The comparison can guide future work and set goals that need to be achieved through materials selection and processing method development.

In this study, the effects of weight fraction of cenosphere on dry sliding wear behavior of Al-Si12 matrix alloy particle reinforced composites, fabricated by squeeze casting technique was investigated. Wear tests were carried out on a pin-ondisc wear tester at 0.5235, 1.0472, 1.5708 and 2.0944 m/s sliding velocity under loads of 5, 10, 15 and 20 N against EN 31 steel disc. The results showed that the higher the load and the faster the sliding velocity are, the higher the wear rate is. The coefficient of friction of the matrix alloy and composites decreased with increase with the load.

In the development of Metal Matrix Composite (MMC), Titanium Carbide (TiC) of 5, 10 and 15 weight percentage has been reinforced in to pure aluminum (Al) using Powder Metallurgy (PM) technique. Aluminum and TiC were mixed in a horizontal ball mill to obtain a uniform mixture followed by pressing in a cylindrical die. Specimens so prepared were subjected to sintering at a two different temperatures of 4000C and 4500C in a tube furnace under nitrogen atmosphere for 4 hours. In this work, an attempt is made to study the influence of TiC in aluminum on physical properties like density, porosity and mechanical properties such as Hardness, Compression strength and Roughness of the surface.

Tribological behavior of aluminium matrix composite (AMC)/brake pad tribo-couple under dry sliding conditions was studied using Pin-on-Disc machine. Brake pad material was used as pins while the AMC formed the rotating disc. Series of experiments were performed to characterize the tribological nature of the tribo-couple. Load and sliding speeds were varied over a range to represent actual braking conditions in passenger cars. Effect of volume fraction and size distribution of reinforcement on wear and friction coefficient has been studied. It was observed that a heterogeneous tribo-layer was formed over the worn surfaces during the wear tests. Presence of tribo-layer was believed to cause two effects: acting as a lubricant layer and acting as a source of wear debris. Morphology and topography of worn surfaces and debris were studied using scanning electron microscope (SEM), electron probe micro analyzer (EPMA), and X-ray diffraction (XRD) techniques. When the reinforcement in the matrix has wide size distribution, wear rate and friction coefficients are found to be higher compared to composite containing mono-size reinforcement.

Composites are most promising materials of recent interest. Metal matrix composites (MMCs) possess significantly improved properties compared to unreinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Hence, composites with fly ash as reinforcement are likely to over come the cost barrier for wide spread applications in automotive and small engine applications. In the present investigation, AA 2024 alloy -2 to 10 wt% fly ash composites were made by stir casting route. Phase identification and structural characterization was carried out on fly ash by X-ray diffraction studies. Scanning electron microscopy and optical microscopy was used for microstructure analysis. The hardness, compression and pitting corrosion tests were carried out on all these alloy and composites. The SEM studies reveal that there was a uniform distribution of fly ash particles in the matrix phase and also very good bonding is exist between the matrix and reinforcement. With increasing the amount of fly ash the density of the composites was decreased and the hardness was increased. The increase in compression strength was observed with increase in amount of fly ash. Fly ash particles lead to an enhanced pitting corrosion of the aluminium-fly ash (ALFA) composites in comparison with unreinforced matrix (AA 2024 alloy). The enhanced pitting corrosion of ALFA composites is associated with the introduction of nobler second phase of fly ash particles.

The articles in this issue look at how the development and use of free and open source hardware (FOSH or simply “open hardware”) are changing the face of science, engineering, business, and law.

Free and open source software (FOSS) has proven very successful and now dominates the development of software on a global scale. It is available in source code (open source) and can be used, studied, copied, modified, and redistributed either without restriction or with restrictions only to ensure that further recipients have the same open source rights.
Similarly, FOSH provides the “code” for hardware—including the bill of materials, schematics, instructions, computer-aided designs, and other information needed to recreate a physical artifact. Use of FOSH can improve product innovation in a wide range of fields. In this issue authors from a variety of disciplines and work environments discuss how this open model of innovation will drive the future of engineering.
First, Alicia Gibb, founder and executive director of the Open Source Hardware Association (OSHWA) and director of the ATLAS1 Blow Things Up (BTU) Lab at the University of Colorado Boulder, argues that hardware is the next step to open sourcing everything. She touches on intellectual property (IP) issues, cites the benefits of open source hardware, introduces and explains the role of OSHWA, and hints at the future of open hardware.

The open source paradigm is already making deep inroads in the hardware space in 3D printing. With the development of the open source RepRap project (a 3D printer that can print itself) the cost of 3D printers has dropped to a point where nearly anyone can afford one for rapid prototyping and small batch manufacturing.

Ben Malouf and Harris Kenny of Aleph Objects describe their company’s approach to the use of open hardware in every aspect of their business to create the popular Lulzbot 3D printer. Their primary product is open—and consistently wins one of the top spots in Make: Magazine’s annual 3D printer shootout, ahead of proprietary 3D printers from much larger companies with far greater resources. Lulzbot printers, and those of many other manufacturers, are rapidly increasing in sales as the number of free and open source 3D printable designs erupts on the Web, making distributed manufacturing a reality.

In this context, law professor Lucas Osborn at the Campbell University School of Law takes us on a deep dive into how IP law will need to change in this new 3D printing era. After summarizing the basics of IP law and explaining why it was created, he discusses how it could both benefit and hinder 3D printing technology. His arguments will challenge readers independent of their views on patent law. For those with conventional IP leanings, he shows how IP law can hinder innovation. For those born in the Internet age, where sharing is second nature and little thought is given to licenses as long as the code is posted on Github, he offers some important lessons. He ends with a challenge for engineers to make more of an effort in helping form IP law that will benefit innovation.
If these lessons on IP and open hardware replication with 3D printers are turned to experimental research in science and engineering, there is an important opportunity to radically reduce the costs of experimental research while improving it. In the next article I argue that by harnessing a scalable open source method, federal funding is spent just once for the development of scientific equipment and then a return on this investment (ROI) is realized by digital replication of scientific devices for only the costs of materials. With numerous examples I show that the ROI climbs into the thousands of percent while accelerating any research that the open paradigm touches. To harness this opportunity, I propose four straightforward and negative-net-cost policies to support FOSH development and improve access to scientific tools in the United States. The policies will directly save millions in research and STEM education expenditures, while providing researchers and students access to better equipment, which will promote advances in technology and concomitant benefits for the American economy.

Thinking about the future and the changes needed to support this development in STEM education, AnnMarie Thomas and Deb Besser of the St. Thomas School of Engineering consider how engineers and engineering educators can use maker methods to introduce students to engineering and build their technological literacy. They show that the maker movement is closely tied to open hardware and sharing as well as the traits of successful engineers. Makerspaces and fabrication (fab) labs (what Gibb calls hackerspaces) are physical hubs of the maker culture.
Although these trends are clearly important for the United States, this cultural change and open hardware ethos can have dramatic impacts in the developing world. Matthew Rogge, Melissa Menke, and William Hoyle of TechforTrade explain the potential for open source and 3D printing to produce many needed items in low-resource settings, where lack of infrastructure makes local production impractical and high tariffs, unreliable supply chains, and economic instability make importation costly. Saving 90 percent on medical or scientific tools is nice in my lab, for instance, but it literally saves lives in a developing world context.
The issue concludes with an op-ed by Tom Callaway, a senior software engineer at Red Hat, Inc., an open source software company with revenue over $2 billion last year (up 15 percent year over year). What makes this business accomplishment so impressive is that all of the company’s software products are available for free. Although old ways of thinking demand that companies secure a monopoly and certainly not give away “intellectual property” for free, Red Hat’s success comes from offering its customers support, collaboration, control, and a high-quality product. Tom argues that the proven open source software mentality is porting to hardware, opening up incredible opportunities for humanity. He concludes, “open source and open innovation work…. They also empower society and make it possible to push the limits of what is possible. When the barriers to collaboration are lifted, people can accomplish incredible things.”

As all of the articles show, open source tools in the hands of this and future generations of engineers will be incredible indeed.

This research is aimed to analysis the effect of holding time, grain size and compacting pressure parameter against compressive strength of Aluminum-5% fly ash using powder metallurgy method. The irregular form and homogeneous particles of aluminum powder used in this research is produced by Merck German, while fly ash is taken from residual combustion coal in forging process in mechanical engineering workshop of Politeknik Negeri Sriwijaya (Polsri) which is mashed up to grains size 140 and 270 mesh, pressed with holding time 60 and 120 seconds, with compacting pressure 139 N/mm 2 and 275 N/mm 2 by cold iso-static pressing. The green body resulted from these processes then sintered up to 550 0 C. Taguchi Method is used to determine factors which affect optimum condition of compressive strength of Aluminum-5% fly ash. The research result using ANOVA show that the holding time, grains size, , and compacting pressure parameters has significantly affect the compressive strength of Aluminum-5% fly ash.

In the present paper eight types of A356 Al-fly ash composites were synthesized using pressure infiltration technique, by utilizing Class C fly ash (FA). Actually, such a strongly calcareous FA was for the first time used in MMCs-manufacturing by liquid metal infiltration techniques. After testing their mineralogy and chemistry, certain FA size-fractions were used for the fabrication of the composites and their particular properties were linked to the level of the successful synthesis of the materials, the development of their microstructure and their wear strengths. The effect of using ground FA particles on the structure of composites and their tribological performance was also investigated through this study. It was concluded that using fine FA particles can strongly advantage the properties of composites and that grinding of fly ash facilitates MMCs-manufacturing by pressure infiltration and it also advantages their wear properties.

In the present paper eight types of A356 Al-fly ash composites were synthesized using pressure infiltration technique, by utilizing Class C fly ash (FA). Actually, such a strongly calcareous FA was for the first time used in MMCs-manufacturing by liquid metal infiltration techniques. After testing their mineralogy and chemistry, certain FA size-fractions were used for the fabrication of the composites and their particular properties were linked to the level of the successful synthesis of the materials, the development of their microstructure and their wear strengths. The effect of using ground FA particles on the structure of composites and their tribological performance was also investigated through this study. It was concluded that using fine FA particles can strongly advantage the properties of composites and that grinding of fly ash facilitates MMCs-manufacturing by pressure infiltration and it also advantages their wear properties.

Aluminum alloys containing fly ash (ALFA -Aluminum Fly Ash) composites have been developed in recent years. The use of fly ash as a filler or reinforcement for aluminum matrix composites is very desirable from an environmental standpoint. However, synthesis of ALFA composites by liquid phase routes is difficult due to poor wettability of fly ash by molten Al and Al alloys at industrially important temperatures and its lightweight nature (particularly for hollow spheres).

In the present paper eight types of A356 Al-fly ash composites were synthesized using pressure infiltration technique, by utilizing Class C fly ash (FA). Actually, such a strongly calcareous FA was for the first time used in MMCs-manufacturing by liquid metal infiltration techniques. After testing their mineralogy and chemistry, certain FA size-fractions were used for the fabrication of the composites and their particular properties were linked to the level of the successful synthesis of the materials, the development of their microstructure and their wear strengths. The effect of using ground FA particles on the structure of composites and their tribological performance was also investigated through this study. It was concluded that using fine FA particles can strongly advantage the properties of composites and that grinding of fly ash facilitates MMCs-manufacturing by pressure infiltration and it also advantages their wear properties.

Aluminum alloys containing fly ash (ALFA -Aluminum Fly Ash) composites have been developed in recent years. The use of fly ash as a filler or reinforcement for aluminum matrix composites is very desirable from an environmental standpoint. However, synthesis of ALFA composites by liquid phase routes is difficult due to poor wettability of fly ash by molten Al and Al alloys at industrially important temperatures and its lightweight nature (particularly for hollow spheres).

In the present paper eight types of A356 Al-fly ash composites were synthesized using pressure infiltration technique, by utilizing Class C fly ash (FA). Actually, such a strongly calcareous FA was for the first time used in MMCs-manufacturing by liquid metal infiltration techniques. After testing their mineralogy and chemistry, certain FA size-fractions were used for the fabrication of the composites and their particular properties were linked to the level of the successful synthesis of the materials, the development of their microstructure and their wear strengths. The effect of using ground FA particles on the structure of composites and their tribological performance was also investigated through this study. It was concluded that using fine FA particles can strongly advantage the properties of composites and that grinding of fly ash facilitates MMCs-manufacturing by pressure infiltration and it also advantages their wear properties.

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al- and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological...

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al-and Al-alloy-based Metal-Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced the tribo-performance of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, the additions of ashes up to 15% wt. resulted in only slight deterioration of the wear performance of composites.

Eight types of A356 Al-fly ash composites were produced by pressure infiltration of high-Ca lignite fly ash. This type of ash was used for the first time in Al-composites synthesis, and particularly by liquid metal infiltration techniques. After examining mineralogy and chemistry, specific, narrow ash size fractions were used for the synthesis of composites, and properties linked to microstructure and wear strength of the materials. The effect of using ground ash particles on the microstructure and tribological performance of the composites was also investigated. It was concluded that using fine, high-Ca ash particles can improve the properties of composites, and that using ash particles in a ground form can better facilitate the production process of MMCs.

In this contribution, authors present a review on the state-ofthe-art in the utilization of industrial and agricultural waste materials for the development of metalÀmatrix composites (MMCs), providing, through the judicious analysis of an ample and varied references source À from the oldest to the newest ones À an insight into the challenges and opportunities for the exploitation to their full potential. In addition to its topicality, the novelty of this contribution lies in the presentation of key statistical, technical, and property-related information of a comprehensive variety of waste materials classed into two main groups, namely, fly ash reinforced MMCs and MMCs derived from other waste materials. Although fly ash has been exploited in a broad range of applications, the attention paid for its use in the development of MMCs seems to be insufficient. A purposely designed chart helped to pinpoint the more demanding and profitable applications of fly ash, and establish strategic opportunity areas. With the exception of the recent utilization of fly ash for the automotive industry, virtually no other waste material has been reused for a specific industrial application. In this context, by identifying five reasons for this observed delay, an essential goal of this review is to arouse the interest of academicians, scientists/technologists, and industrialists in the use of those materials for the fabrication of MMCs. In the case of agricultural materials, a twofold perspective may apply, because while on the one hand, certain chemical elements have to be removed for specific applications, on the other hand, recovery of certain elements might be more attractive. Based on the significant progress observed so far, in terms of scientific and technological research, a promising future can be anticipated. The proper use of industrial and agricultural waste materials entails knowledge generation as a prerequisite for incubation of pilot-plant and industrialization stages, culminating with all related benefits to society.

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al- and Al-alloy-based Metal-
Matrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing
10–20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites
was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior
using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM
and Energy Dispersive X-Ray Spectroscopy (EDS). It was shown that the addition of both types of FA enhanced triboperformance
of Al, with the optimum metal powder replacement determined to the point of 15% wt., in the case of high-Si and 10% wt., in the case of high-Ca ash particles. Regarding alloy-matrix composites, although they generally presented worse tribological performance than pure Al/Si products, addition of ashes up to 15% wt. resulted in only slight deterioration of the
wear performance of composites.

In the present paper eight types of A356 Al-fly ash composites were synthesized using pressure infiltration technique, by utilizing Class C fly ash (FA). Actually, such a strongly calcareous FA was for the first time used in MMCs-manufacturing by liquid metal infiltration techniques. After testing their mineralogy and chemistry, certain FA size-fractions were used for the fabrication of the composites and their particular properties were linked to the level of the successful synthesis of the materials, the development of their microstructure and their wear strengths. The effect of using ground FA particles on the structure of composites and their tribological performance was also investigated through this study. It was concluded that using fine FA particles can strongly advantage the properties of composites and that grinding of fly ash facilitates MMCs-manufacturing by pressure infiltration and it also advantages their wear properties.

(The present patent describes the Herbots-Atluri process to synthesize oxide nanophases, interphases and precursor phases on Si(100) and other group IV, IV-IV, IV-IV-IV, and other semicondictors. The keypoints of the methodology are: (1) nano-scale planarization using a unique sequencing of chemical oxidation and etching, which can be conducted using wet or dry chemistry, including spin-etching. The planarization yields on Si(100) atomic terrace step densities that are at least one order of magnitude lower than conventional, RCA- and Kern-based processes. (2) nucleation of a  two-dimensional precursor using siloxane termination (Si2O2H4) rather than SiH to produce a passivated, stable surface that remains ordered at room temperature in ambient air). A semiconductor processing method capable of producing highly ordered, ultra thin dielectrics, including gate oxide and other semiconductor dielectrics, and interphase phases with low defect density. The process includes a degrease step, an etch, primary oxidation and then a passivation step which utilizes hydrofluoric acid to passivate the cleaned silicon surface with hydrogen. Dielectric layers may then be formed with low interface defect density, low flat band voltages and low fixed charge on semiconductor substrates.