The preferred orientation of polyacrylnitrile (PAN)-based carbon fibers, mesophase pitch-derived carbon fibers, and pitch precursor fibers was studied by using x-ray diffraction technique. The half width at half maximum (HWHM) intensity of the φ scan x-ray diffraction profiles of these fibers was a minimum at around 2θ = 26°. The result implies that a crystallite with a larger coherence length of crystallite size Lc(002) is better aligned along the fiber axis than that with a smaller Lc(002) in these fibers. Further, θ-2θ scan profiles depending on φ showed that a better aligned crystallite possesses a larger Lc(002) than a misaligned one. Lc(002) of a significantly misoriented crystallite remained constant at about 2 nm even after heat-treatment, though Lc(002) of a well-aligned crystallite was easily changed by heat-treatment for both PAN and pitch-based fibers. The pitch precursor fiber exhibited a clear peak at about 2θ = 7° in the θ-2θ profile and unusual ° scan profiles for 2θ around 7°, which were explained by assuming columnar structures formed by molecule stacking along the c-axis with periodic arrangements of the columns perpendicular to the c-axis. The periodic column stacking structure observed in the pitch precursor fiber was also detected in pitch-based carbon fibers heat-treated at lower temperatures.

Polycarbonate (Lexan) was implanted with 100 and 200 keV B+ ions to doses of 0.26, 0.78, and 2.6 × 1015 ions/cm2 at room temperature (<100 °C). Mechanical characterization of implanted materials was carried out by nanoindentation and sliding wear tests. The results showed that the hardness of implanted polycarbonate increased with increasing ion energy and dose, attaining hardness up to 3.2 GPa at a dose of 2.6 × 1015 ions/cm2 for 200 keV ions, which is more than 10 times that of the unimplanted polymer. Wear properties were characterized using a reciprocating tribometer with nylon, brass, and SAE 52100 Cr-steel balls with 0.5 and 1 N normal forces for 10000 cycles. The wear mode varied widely as a function of ion energy, dose, wear ball type, and normal load. For given ion energy, load, and ball type conditions, there was an optimum dose that produced the greatest wear resistance and lowest friction coefficient. For polycarbonate implanted with 0.78 × 1015 ions/cm2, the nylon ball produced no wear after 10000 cycles. Moreover, the overall friction coefficient was reduced by over 40% by implantation. The results suggest that the potential of ion-beam technology for improving polycarbonate is significant, and that surface-sensitive mechanical properties can be tailored to meet the requirements for applications demanding hardness, wear, and abrasion resistance.

Photochemical modification of the polytetrafluoroethylene (PTFE) with incorporation of the CH3 radical released from the B(CH3)3 molecule excited by an ArF excimer laser has been demonstrated. The incorporation of CH3 radicals and the depletion of fluorine atoms of the polymer surface were studied by XPS analysis and infrared ATR spectrum measurement. In these photochemical reactions, the photoirradiated surface changed into oleophilic. The properties were studied by contact angle measurement. The stability of the oleophilic surface was examined at the elevated temperature of 200 °C for 6 h in O2 or N2 ambient and also by immersing in alkaline or acid water solutions.

Subcritical crack growth behavior along polymer/glass interfaces was measured for various epoxy adhesives at different relative humidities. A four-point flexure apparatus coupled with an inverted microscope allowed for observation in situ of the subcritical crack growth at the polymer/glass interface. The specimens consisted of soda-lime glass plates bonded together with epoxy acrylate, epoxy (Devcon), or epoxy (Shell) adhesives. Above a threshold strain energy release rate, the subcritical crack velocity was dependent on the strain energy release rate via a power law relationship where the exponent was independent of the adhesive tested and the test humidity (n = 3). However, the multiplicative constant A in the power law relation varied by over three orders of magnitude between the various adhesives with epoxy (Shell) having the smallest value and the epoxy (Devcon) the greatest value; in addition, A was very sensitive to humidity, decreasing by over two orders of magnitude from 80% to 15% relative humidity. At high strain energy release rates, the subcritical crack velocity reached a plateau at approximately 10−6 m/s. The use of this subcritical crack velocity data in predicting thin film delamination is discussed.

The first suspensions of rod-shaped dielectric particles in an infrared transmitting solvent are reported. Specifically, micron size β–FeOOH rods have been produced in chloroform, carbon tetrachloride, and carbon disulfide. A technique to transfer the particles from water into organic solvents is demonstrated and a novel optical method to determine the degree of stability of the organosols is used. Sedimentation times vary with preparation technique over the range of minutes to hours, often being long enough to allow the use of the material as an infrared Kerr medium with large electric field induced birefringence. Dispersions in hexane, which has good microwave transmission, have also been produced.

Ultrasonic energy was used to accelerate the formation of hydroxyapatite (HAp). The experiments were carried out in aqueous systems on two different sets of reactants: (1) a mixture of Ca4(PO4)2O(TetCP) and CaHPO4 · 2H2O (brushite) and (2) α–Ca3(PO4)2 (α–TCP). The reaction systems were exposed to ultrasound of 20 kHz for various times ranging from 5 to 80 min. The products were characterized by XRD and SEM. Parallel experiments without ultrasound were carried out for calibration. The results show that the ultrasound substantially accelerates both reactions. With ultrasound, the time required for the TetCP-brushite system to complete the reaction forming HAp was reduced from 9 h to 25 min at 25 °C, and from 3 h to 15 min at 38 °C. At 87 °C, α–TCP does not hydrolyze within 1 h in de-ionized water unless the pH is adjusted. Hydrolysis of α–TCP was induced by sonication in less than 20 min, and longer treatment results in the formation of a homogeneous sol of HAp.

The properties of the Y1−xPrxBa2Cu3O7 (YPrBCO) system are reviewed. These include superconducting, normal state, structural, chemical, optical, magnetic, and thermal properties. The destruction of superconductivity with Pr doping is discussed in view of possible models such as hole filling, localization, magnetic pair-breaking, and the role of hybridization. Applications to electronic devices using YBCO/PrBCO/YBCO multilayers are also reviewed.

Specimen length-to-diameter ratios and specimen/platen end conditions are important to interpretation of, and comparisons between, uniaxial compression tests on brittle materials. When differing l:d ratios and specimen/platen end conditions are used to test pressure-sensitive materials, observations may not be readily comparable owing to the different and nonuniform triaxial stress states. Specimens of brittle Fe- and Ni-modified Al3Ti intermetallic alloys having relatively low and different l:d ratios were tested in compression by Gengxiang et al. and Turner et al., respectively. Qualitative observations on the macroscopic deformation and failure modes (shear failure and distributed microcracking) indicate that the alloys are pressure-sensitive and that the results were possibly complicated in differing degrees by test configuration. Thus, direct comparison of these results with those obtained earlier for Al3Ti by Yamaguchi et al., who used a significantly greater l:d ratio, may not be altogether useful. Approaches to minimizing end effects are reviewed.

Compression test results of our research on Al3Ti-base alloys are reported. It is evident that the specimen length-to-width ratio we used for compression testing can significantly reflect the difference in ductility of different alloys. Thus the tests fulfilled the aim of our present research.