CVD diamond coated tools are developed for applications as different as turning of cemented carbides and bone drilling. The diamond films are deposited by Hot Filament Chemical Vapor Deposition (HFCVD), with grain sizes varying from conventional micrometric (12 μm) to nanometric (< 100 nm) and film thickness up to 50 μm. Silicon nitride (Si3N4) ceramics are chosen for the base material in order to guarantee maximal adhesion. Both the micrometric and nanometric CVD diamond grades endure the cemented carbide turning showing slight cratering, having flank wear as the main wear mode. However, nanocrystalline diamond present the best behavior regarding cutting forces (<150 N) and tool wear (KM=30 μm, KT=2 μm and VB=110 μm) and workpiece surface finishing (Ra=0.2 μm). In the case of the dental drilling experiments, a polymeric laminated test block is used to simulate the human mandible and maxilla. The temperature rise during drilling is monitored to prevent overheating above 42–47 °C that is known to cause tissue death and implant failure. It is possible to drill with a CVD diamond Si3N4 coated tool with significantly lower forces (fourfold smaller), lower rise in temperature (4°C less), lower spindle speeds (100 rpm) and higher infeed rates (30 mm/min), when compared to the commercial steel (AISI 420) drill bits.

In recent years, the increasing energy costs have lead to power utility industries to seek/develop high efficiency systems of production and of energy utilization. In addition, environmental concerns regarding greenhouse gas emissions are playing a major role in the development of clean energy systems. The development of metallic materials that can withstand elevated temperatures is among the viable alternatives to increase energy efficiency. Nevertheless, for this to happen, the corrosion and oxidation resistance of Fe- and Ni-based alloys needs to be significantly improved. Among the possible ways to enhance the life of high temperature alloys is the application of protective ceramic coatings. Conventional coatings are expensive and the protective effects controversial at times. An alternative which offers a great potential is the application of nano-ceramic coatings. Hence, in this work nanocrystalline coatings based on nano-CeO2 are applied to an austenitic stainless steel 304L and then exposed to elevated temperatures. Weight changes are monitored as a function of time and the results are compared with uncoated alloys tested under similar conditions. In addition, computer simulations of possible rate limiting diffusion mechanisms are carried out. It is found that the nanocoatings provided remarkable high-temperature oxidation resistance and improved scale adhesion. In particular, it is found that the smaller the nanoparticles are, the more effective the nanocoatings in providing oxidation resistance.

This research work deals the influence of boron content on the high temperature deformation behavior of a low carbon advanced high strength steel (AHSS). For this purpose high temperature tensile and compression tests are carried out at different temperatures and constant true strain rates by using an Instron testing machine equipped with a radiant cylindrical furnace. Tensile tests are carried out at different temperatures (650, 750, 800, 900 and 1000°C) at a constant true strain rate of 0.001 s-1. Uniaxial hot compression tests are also performed over a wide range of temperatures (950, 1000, 1050 and 1100°C) and constant true strain rates (10-3, 10-2 and 10-1 s-1). In general, experimental results of hot tensile tests show an improvement of the hot ductility of the AHSS microalloyed with boron, although poor ductility at low temperatures (650 and 750°C). The fracture surfaces of the AHSS tested at temperatures showing the higher ductility (800, 900 and 1000°C) indicate that the fracture mode is a result of ductile failure, whereas in the region of poor ductility the fracture mode is of the ductile-brittle type failure. On the other hand, experimental results of hot compression tests show that both peak stress and peak strain tend to decrease in the AHSS microalloyed with boron, which indicates that boron generates a sort of solid solution softening effect in similar a way to other interstitial alloying elements in steel. Likewise, hot flow curves of the AHSS microalloyed with boron show an acceleration of the onset of dynamic recrystallization (DRX) and a delay of the recrystallization kinetics. Results are discussed in terms of boron segregation towards austenitic grain boundaries and second phase particles precipitation during plastic deformation and cooling.

In this work, results are presented regarding the characterization of nanostructured Fe matrix composites reinforced with fullerene. The fullerene is a mix of 15 wt.%C60, 5 wt.%C70 and 80 wt.% soot that is the product of the primary synthesis of C60. The composite has been produced by means of mechanical alloying and sintered by Spark Plasma Sintering (SPS). The characterization methods include XRD, SEM and TEM. The C60 and C70 withstand mechanical alloying, SPS, and thermomechanical processing and act as a control agent during mechanical alloying. The results show that the mechanically alloyed and SPS product is a nanostructured composite. A larger amount of C60 is found in the sintered composite than in the original fullerene mix, which is attributed to an in-situ synthesis of C60 during the SPS process. The synthesis of C60 is presumably assisted by the catalytic nature of Fe and the electric field generated during the SPS process. In order to study the effect of high temperature, high strain, high heating and cooling rates on C60, the composite is subjected to a thermomechanical processing; demonstrating that some of the C60 resists the above described environment and some of it partially transforms into diamond.

Ni-P and Ni-P-Al2O3 composite coatings are obtained by electroless plating on steel substrates. Alumina particles with an average particle size of 5 microns are added to the bath in loads of 5, 10, 15 and 20g/L. It is found a maximum retention of 18.2 vol.% Al2O3 for a ceramic load of 10g/L. The composition of the binary Ni-P deposits is 9.3 wt.% P and the balance nickel. The addition of ceramics to the electroless solution induces a reduction of phosphorous content to 9.0, 8.3, 7.9 and 7.3%, respectively. The deposited coatings are heat-treated in the temperature range between 100 and 500°C and holding times from 30 to 300 minutes. A maximum hardness of 1600 HV0.1 is obtained for composite coatings containing 18.2 vol.% Al2O3 treated at 400 °C/1h. The uniform distribution of ceramics and precipitation of fine Ni3P and Ni12P5 precipitates are responsible of the hardening of the nickel matrix.

This paper presents a thermochemical method, based on a mixture of molten alkaline halides to produce a Ti coating on AISI 316L stainless steel. The thickness of the coatings is a function of temperature and time. It is observed that the physical form of the Ti source employed affects both coating thickness and morphology. The formation of several inter-diffusion layers is detected, each having a characteristic chemical composition, morphology and location at the substrate/coating interface. It is proposed that some of the produced Ti coatings can be employed to improve osseointegration of stainless steel for potential prosthetic devices.

Ti-coated AISI 316L stainless steel, for potential biomedical applications, is obtained by thermal decomposition of TiH2 under vacuum. The presence of hydrogen in the coating material facilitates the sintering process of Ti particles, with simultaneous formation of several inter-diffusion layers at the substrate/coating interface, whose thickness and chemical composition depend mainly on the treatment temperature. Coatings prepared at 1100°C exhibit formation of a wide zone at the substrate/coating interface, which is associated with the appearance of cracks, and which consists of a mixture of λ + χ + α-Fe phases. Formation of abundant microporosity is also observed in this region, which is attributed to the Kinkerdall effect.

The effect of plastic deformation and subsequent annealing on the microstructure and magnetic properties (hysteresis core losses) of non-oriented grain semi-processed Si-Al electrical steel sheet are investigated. Plastic deformation of strip samples is performed by cold-rolling (5–20% reduction in thickness) along the original rolling direction. Annealing is carried out in air during 1 or 60 minutes at temperatures between 650 and 850°C. Measurements of B-H hysteresis curves are performed using a Vibrating Sample Magnetometer and characterization of annealed microstructures is carried out using optical metallography. The results show that hysteresis losses increase by a factor between 1.2 and 2.0 as the magnitude of the applied plastic deformation increases from 5 to 20% reduction in thickness. The rate of recovery of energy losses as a result of annealing depends on annealing time. Short annealing times produce full recovery of the effect of cold work and values of energy losses lower than in undeformed material. The magnitude of the additional recovery increases with strain but does not depend on annealing temperature. Long annealing times, which induce complete recrystallization, and either normal or abnormal grain growth, enhance recovery of hysteresis losses. The rate of recovery increases as both the strain and annealing temperature increase. Recovery of the deformation microstructure and internal stress relief produce only limited recovery of the magnetic properties. However, recrystallization and grain growth brings about a significant decrease in hysteresis losses.

An experimental study on the effect of tensile deformation on recrystallized grain size has been carried out in order to establishing the optimal deformation needed to accelerate grain growth during final annealing of semi-processed non-oriented Si-Al, low C electrical steel sheets. The material is deformed in tension to strains from 3 to 20% and then air-annealed at temperatures between 700 and 900 °C. The results show that the critical deformation for recrystallization (8%) is independent of annealing temperature. However, the critical recrystallized grain size increases with annealing temperature from 160 to 240 μm. After that, the grain size decreases exponentially with increasing deformation. Abnormal grain growth is observed in samples annealed at 700 °C after strains in the range from 7 to 12%. This type of behavior is also observed in specimens annealed at 800 and 900 °C, however, in this case the pre-strain range is expanded to 3–12%. Normal grain growth is observed in samples pre-deformed to strains larger than 12%. In this case, the final grain size after 2 hour anneal is about 55 μm, also independent of annealing temperature. The possible implications of these results on the magnetic properties of these materials are discussed.

Cyclodextrin (CD) has been studied intensively due to its ability to form inclusion complexes with a variety of guest molecules in the solid state. A few studies have paid attention to the use of CD to facilitate the synthesis of inorganic nanoparticles. In this work the synthesis of magnetite (M) is made in the presence of CD. The particle size of the inorganic material is controlled by the presence of CD, in which spherical particles of few nanometers are grown. The synthesis of Fe3O4 (M) in the presence of α-cyclodextrin (α-CD) and β-cyclodextrin (βCD) is described. The formation of an M-CD complex is studied in both cases by Fourier transform infrared spectroscopy (FT-IR) in order to elucidate the chemical bonding of the complex. The morphology and size of the particles are determined by Field Emission Scanning Electron Microscopy (FESEM) and software. X-ray diffraction (XRD) is used to confirm the formation of magnetite.

In this work the synthesis of functional gradient materials (FGMs) through the nitriding in salts of previously fabricated cermets is carried out. The matrix for the preparation of the FGMs is made of an Al2O3-based cermet with a fine and homogeneous dispersions of metallic particles of Al, Ti and Fe, the final content of the metallic particles in the cermets is of 10 vol. %. These materials are synthesized by powders techniques, considering as variable of study the reinforcement metal in the cermet, previous to sinter, cylindrical samples of the corresponding cermet are uniaxially compacted using 200 MPa. Subsequently, all sintered cermets are characterized by microstructural observations with the help of light microscopy. Obtained cermets are then submitted to a nitriding process by immersion in ammoniac salts. The objective is to attain a compositional gradient of metal-nitrides at the surface. This is done through a chemical reaction between the metallic particles at the cermets' surface and the nitrogen released by the ammonia salts. Functional materials are obtained such as; Al2O3–Al–AlN and Al2O3–Ti–TiN.

Two alternative chemical methods are studied for the extraction of Al2O3 from Mexican Fly Ash (FA). Reaction of FA with H2SO4 at high temperature allows extracting ∼37% of the total Al2O3 contained in the FA as Al2(SO4)3, regardless of H2SO4 concentration, treatment time and temperature employed. This is partly due to the high chemical resistance of mullite (Al6Si2O13) contained in the FA. In contrast, reaction of FA with a CaCO3-Na2CO3 mixture at 1300°C/1h, followed by lixiviation with a Na2CO3 aqueous solution and precipitation of bohemite [AlO(OH)] by addition of either H2O2 or NH4HCO3, allows extracting ∼80% of the total Al2O3 contained in the FA as θ-alumina, after calcination of bohemite at 1200°C/1h.

In this work, a commercial zircon flour of 99% purity and mean particle size of 10μm is used. Suspension stabilization process is carried out using the electrostatic stabilization mechanism at pH 11 employing Tetramethylammonium hydroxide (TMAH). Tape casting suspensions are formulated with binding systems obtained by the combination of polyvinyl alcohol with polyethylene glycol, additionally the binding system is added at different binder:plasticizer ratio ranging from 1:1 to 3:1. Suspensions are characterized rheologically determining its type and flow properties by obtaining flow and viscosity curves. Suspensions are tape cast on vinyl-acetate substrates and are dried at room conditions to determine some physical properties of the obtained tapes and to correlate the rheological with the physical properties. The experimental results show that tape casting suspensions have a shear thinning flow type, yield points and flow indexes varying as a function of binder system combination and binder:plasticizer ratio. Also, the binder system has a strong influence on the green tapes characteristics.

This work reports the thermoelectric characterization of a hydrogen embrittlement (HE) of low strength steel. Two sets of tests are performed in an electrochemical cell of H2SO4, with and without applied stress, lasting from 2 to 94 hours. Thermoelectric power (TEP) measurements are matched with ductility measurements (%RA and %EL) of samples tested in tension, as well as with microhardness measurements. Results indicate that TEP is sensitive to HE of low strength steels; the maximum variation of TEP is of ∼80nV/°C for samples tested without stress.

Effects of hot band annealing on the final microstructure and magnetic properties of cold rolled and annealed non-oriented grain Si-Al electrical steel strips are investigated. Microstructures are characterized using optical and scanning electron microscopy and magnetic properties are determined using a vibrating sample magnetometer. It is shown that annealing of hot rolled bands at temperatures between 800 and 850 °C causes rapid decarburization and development of a microstructure consisting of large columnar ferrite grains free of secondary particles. This microstructure leads, after cold rolling and a fast annealing treatment, to large grain microstructures similar to those observed in production scale, fully processed strips. It is observed that the final grain size increases with the final annealing temperature, leading to a significant improvement of the magnetic properties. Therefore, hot band annealing technology can be an attractive alternative processing route for the manufacture of non-oriented grain low carbon Si-Al processed electrical steel strips.

An experimental study of the mechanical properties of a Cu-Al-Be shape memory alloy is presented. The samples are tested in a cantilever arrangement. They consist of polycrystalline thin plates of shape memory material with a MS near 0 °C and a monocrystalline sample with MS near −90 °C. The measurements are made with strain gauges attached to the top side of the samples. In these conditions, strain Vs load curves are obtained. A polycrystalline sample is instrumented and tested and then it is cut into three samples for further testing. The results show a relationship between the transformation stress and the sample grain size which differs from the typical Hall-Petch relationship. The analysis of transformation plane stress diagrams shows the development of a stress component perpendicular to those induced by the applied load.

This contribution presents the results obtained by a Mexican laboratory in the Asia-Pacific Economy Cooperation Interlaboratory Comparison (IC) on mechanical properties by nanoindentation from 2008 using fused silica and polycarbonate as samples. Reduced modulus and indentation hardness are the parameters asked to be measured and compared. The aim for this paper is to show and to discuss the so called “indentation size effect” (ISE) on the indentation hardness of fused silica. Using the spherical formulation of the ISE model for crystalline materials, the macroscopic hardness and material length scale of fused silica are determined as (7.34 ± 0.085) GPa and (166.36 ± 14) nm, respectively.

Polyurethanes are interesting materials that can be used in biomedical applications for regeneration of bone tissue. In this work the synthesis and characterization of porous polyurethanes to act as scaffold is performed by a thermally induced phase separation technique. The appropriate parameters are determined in order to obtain a porous well interconnected material. Characterization by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is made in order to determine the thermal stability of the material. Chemical characterization is made by Fourier transformed infrared spectroscopy with attenuated total reflectance (FTIR-ATR). The morphology of the material is observed by a field emission scanning electron microscope (FESEM) and the mechanical properties are measured by dynamic mechanical analysis (DMA).

Glass-ceramics based on hypo-eutectic (GC1) and hyper-eutectic (GC2) compositions of the Wollastonite (W, CaSiO3) - Tricalcium Phosphate [TCP, Ca3(PO4)2] binary system, which are saturated with SiO2 during the glass melting stage, are synthesized by the petrurgic method, using cooling rates of 0.5, 1 or 2°C/h. All synthesized materials are subjected to in vitro bioactivity tests using Kokubo's Simulated Body Fluid (SBF). Primary a-Cristobalite is formed in all cases. Metastable Apatite [Ap, Ca10(PO4)6O] and W phases are additionally formed, in general, in the GC1 glass-ceramics, as well as in the GC2 material obtained at a cooling rate of 0.5°C/h. However, at faster cooling rates, TCP is formed instead of Ap phase in the latter composition. During the bioactivity tests, a hydroxyapatite [HAp, Ca10(PO4)6(OH)2]-like surface layer is formed in all materials. It is proposed that GC2 glass-ceramics cooled at a rate of 1°C/h have the potential to show good in vivo osseointegration properties.

Aluminum-based composites prepared from pure Al powder and previously Cu metallized graphite are fabricated by a solid state route and are characterized by X-ray diffraction and scanning electron microscopy in order to follow their microstructural evolution. Composites are processed using powder metallurgy technique in order to obtain cylindrical samples to carry out mechanical testing. Microstructural and mechanical characterizations reveal that, by milling, a homogeneous dispersion of insoluble particles into the Al matrix is obtained; this produces an important improvement in hardness and strength with respect to an un-milled sample. Milling intensity and particle concentration have an important effect on the mechanical properties of the synthesized composites.