The behavior of viscoelastic hemispherical shells was investigated under internal blast loading. It has been revealed in the process of calculation-experiment research of dynamic viscoelastic properties of structural polymeric materials that glassy polymers change sharply their viscoelastic characteristics. Unlike to mechanical glass transition to glassy state glassy polymers showed ability to transfer into the high-elastic state as a result of elastic energy dissipation.

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Electrical conductivity of high oriented pyrolytic graphite with disorientation in single crystal blocks 1° was investigated under multiple shock-wave compression. It was found when the amplitude of first shock wave exceeds the pressure of graphite - diamond phase transition there occurs martencite conversion during ns time rage. Preliminary dynamic loading by the pressure below 21' GPa increased the transition time by to orders. The unusual sharp reversible increase in electrical conductivity at 55 GPa against the background of the pressure continuing to increase was found.

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This thesis gives an estimation and analysis on the unloading curve P-T of detonation products, and the crystallization process of liquid carbons in Taylor's isentropic regime, which supports the experimental results that ultradispersed diamonds are formed from liquid phase.

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Methods are presented for the forming of articles during shock compaction of powders in the cylindrical configuration. The forming methods make use of mandrels of either a polymer or a metal, since those materials can easily be machined in the required shape. The polymer mandrel decomposes during the shock compression process, forming a hole in the compact with the dimensions of the mandrel. Aluminum mandrels do not decompose, but may change their shape during the compaction process. The aluminum of the mandrel can also be used for a subsequent melt infiltration of the remaining pores in the compacts. In this way fully dense venturi shaped nozzles of TiB₂-Al have been fabricated.

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Recent experimental studies by Hauver et al. reveal that the ballistic performance of ceramic targets depends entirely on the state of confinement of a ceramic in a composite target. If the ceramic confinement is preserved, the penetrator is consumed by lateral flow at the ceramic-cover plate interface; this mechanism is known as interface defeat. In the experiments reported in this paper, stress histories produced at the cover plate-ceramic interface and ceramic-back plate interface are recorded with in-material gauges. Velocity measurements, at the back plate free surface, are recorded with VISAR. Partial interface defeat of the L/D 20 tungsten long rods shot at 1. 7 km/s, on composite targets containing alumina and Titanium diboride ceramics, was obtained.

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Shock stress profile has been measured for polymer materials by the DYNASEN PVDF stress gauge in around 0. 5 GPa stress region. Evolution of the profile with the propagation distance for PMMA and polyethylene has been characterized by the relaxation time and the ratio of stress at the front to the asymptotic value. The change of the ratio of the instantaneous stress value to that of the asymptotic stress and the relaxation time has been obtained.

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Shock induced reaction mechanism is described by investigating the shock reactivity from the pretreated powders by the mechanical alloying. Ti-Al system was employed in the present study to experimentally demonstrate that mass mixing and severe shear deformation process is necessary to ignite the shock induced reaction during the rise time of shock loading pulse and that regularization process from the solid solution or the amorphous phase to intermetallic compounds should be present during the shock loading.

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A new estimate of the threshold condition is proposed for shock-induced chemical reactions in inorganic powder mixtures. The condition is based on a concept of energy balance whereby a sudden increase in interface areas is equated to fluctuating local kinetic energy. Estimates based on the analysis for Ni/Al and Ti/Si compare well with recent real time measurements.

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The measurement of the temperature history of a powder during the shock compaction process requires a very fast measuring principle. Since the response time of normal thermocouples is too slow for the extremely fast temperature changes occurring in the shock compression of powders, here thermocouples formed by the powder to be compacted are used. The temperature measurements are performed in the cylindrical configuration. Copper and constantan powders are used in the development of the measuring technique. This resulted in measurements of the temperature history in these metallic materials. To be able to investigate whether the temperature history during the shock compaction of ceramics differs from that of metals, two ceramic materials TiB₂ and WC) were selected to be used as a powder thermocouple for future work.

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Conductivity measurements indicate that hydrogen becomes a metallic fluid at 140 GPa, ninefold initial liquid density, and ∼3000 K. Metallization occurs when the electronic energy gap E_g is reduced by pressure to k_BT . High pressures and temperatures were obtained by a shock wave reverberating in hydrogen between stiff Al₂O₃ anvils. Resistivity decreases four orders of magnitude from 93 to 140 GPa and is constant from 140 to 180 GPa. About ∼5% of the H₂ molecules are dissociated at metallization . The free-electron Fermi energy is ∼12 ev. The measured conductivities of hydrogen are essentially the same as those of fluid Cs and Rb at 2000 K undergoing the same transition. The transition to the metal occurs at a Mott-scaled density of D_m^1/3a*=0. 30, where D_m is the metallization density and a* is the Bohr radius of the molecule. The measured metallic conductivity is in good agreement with (1) the calculated minimum conductivity of a metal, (2) the conductivity of hydrogen calculated with the strong-scattering free-electron model, (3) a preliminary calculation by Louis and Ashcroft using the weak-scattering Ziman model for a molecular liquid metal, and (4) tight-binding molecular dynamics calculations by Lenosky et al.

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A simple one-dimensional hydrodynamic model is developed for a possible characterization of the laser-driven flyer experiment. The model contains the hydrodynamics and the physics of energy transfer in a simple form. For thin aluminum flyer, the calculated velocities and reflectivitiy/absorption represent corresponding experimental data approximately. Characteristics of the physical process and the simple model are discussed.

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Table-top laser-driven shock loading device was developed to make real time measurement of stress and particle velocity histories during shock loading. Use of a shock cell enables us to launch any-type of mini-flyer with the specified speed by controlling the laser power. Since the VISAR system is equipped with the present shock loading device, Hugoniot data can be obtained by the conventional set-up, where the target material is sandwiched by the mini-flyer and the window material. Accuracy in measurement is discussed for copper and PMMA Hugoniots.

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The need for high enthalpy facilities for simulating the atmospheric entry of bodies has required the development of hypervelocity wind tunnels. From the various possibilities to produce stagnation enthalpies in the range up to 20 MJ/kg the shock tunnels still are very attractive. The required high temperature driver is accomplished in the present work by a oxyhydrogen detonation in the driver section of the shock tunnel. To study the performance range of such a driver type we investigated the behaviour of a detonation driven shock tube. The experimental research aimed at the improvement of the diaphragms, the history of pressures and the structural stresses.

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Indirectly-driven laser-produced shocks have been used to perform absolute equation of state measurements of low-Z solids in the pressure regime above 10 Mbar (1 TPa). The materials examined here are polystyrene and beryllium, two candidate materials for ablators in inertial confinement fusion ignition target designs. The measurements were made in regimes in which the materials are expected to perform in ignition targets.

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The pressure, arising at passage of the large pulse current through the cylindrical liner, can be used for creation of super-high pressure and pulse compression of specimens. Such pressure is necessary for various physical researches, for study of phase conversions of substances. The installation for creation of the pulse pressure in the z-pinch scheme is described in the paper. The installation is connected to the terminal of E7-25 Capacitive Energy Store and it is designed on 10 MA current pulse with 20 kV voltage. The first test results of the installation are submitted.

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Using a moderate energy picosecond pulse laser, 4 GPa shock waves are reproducibly generated at a high repetition rate in molecular solids. These tiny but powerful shocks are termed “nanoshocks”. Time resolved vibrational spectra with high signal to noise can be obtained using coherent anti-Stokes Raman scattering (CARS). Applications of nanoshocks in research and industry are discussed briefly. Results are presented on a molecular crystal, anthracene, and an energetic material, NTO. The temperature and pressure of the shocked material, and the risetime and velocity of the shock front are determined spectroscopically. Ultrafast material relaxation processes are investigated.

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Nitromethane has been studied as a model of energetic aliphatic nitro-compound. The initiation of the decomposition mechanism of nitromethane in the vicinity of the temperature and pressure conditions of explosion has been studied under high static pressure by Raman spectroscopy. The vibrational modes v_a (NO₂) and, in a smaller scale, v_s (NO₂) show a specific behavior at the solid (II) -solid (III) 7. 5 GPa transition (at ambient temperature). The comparison of the Raman spectrum of nitromethane-h₃ with new Raman spectroscopic results under pressure of nitromethane-d₃, nitroethane and tetranitromethane allows to characterize a physico-chemical behavior of these compounds in relation with their exploding properties.

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The detonation behavior of carbon-rich high explosives is affected by a slow coagulation of carbon atoms by diffusion and their possible transformation from one chemical bonding type to another. We have examined the applicability of the Brenner potential at high pressure and high temperature by molecular dynamics simulations and the stability and barrier height between graphitic and diamond clusters as a function of cluster size by quantum chemical calculations. The diffusion kinetics of carbon clusters have been examined by including a time-dependent surface correction to the Gibbs free energy of these clusters.

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Pressure measurement at the center of imploding detonation waves was carried out using a piezofilm stress gauge (PVF₂). From the present measurement, the maximum pressures averaged within 2 and 3 mm in radius from the geometric implosion center are almost proportional to the initial pressure;P_{max (r=2mm)} = P_O × 1. 2 × 10⁴ and P_{max (r=3mm)} = P_O × 9. 0 × 10³. The measured pressure is compared with estimated one based on the selfsimilar solution of imploding shock waves.

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An ultrahigh-pressure apparatus based on thermal energy is devised. In this apparatus, a sample inside the diamond anvil cell is irradiated with pulse YAG laser beam through diamond anvil. High pressure is generated by constraining thermal expansion of ultrahigh temperature region. The apparatus is equipped with a pressure measuring system based on the ruby fluorescence method. In order to examine the ultrahigh pressure ability of the apparatus, an aluminum particle put in 4:1 methanol/ethanol used as pressure medium was irradiated with a laser pulse.

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A shock wave implosion in an axisymmetric cavity filled in with a perfect gas and confined by plane and spherical surfaces which touch one another at the symmetry axis is analyzed numerically. The numerical approach is based on a locally adaptive unstructured grid technique and high-order accurate Godunov-type non-oscillatory scheme for the Euler equations. The increase in gas density and pressure as the converging shock wave approaches the axis is shown to be more intense than that by cylindrical or spherical shock implosion. A good agreement with analytical predictions and the experiment on hand is achieved.

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Cylindrically imploding strong shocks have been generated in solid by the simultaneous detonation of cylindrical high explosive PBX shell. At first the outermost etched copper mesh on a film cylinder is exploded using a high voltage impulsive current, initiating low-density PETN shell. The PETN detonation gas blows off a cylindrical thin flyer, which collides with the inner PBX shell initiating its surface. As preliminary studies, the feasibility of newly developed etched copper mesh for the PETN detonation, cylindrical flyer acceleration systems and shock initiation of the PBX were investigated. Observed shadowgraph of imploding shocks in PMMA cylinder (40mmφ dia. ) shows that cylindrical strong shock wave has focused accelerating with a fairly good axisymmetry, and the comparison with numerical results indicates that the actual steady state C-J pressure of the PBX seems to be almost achieved.

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Tungsten carbide powder with 3. 5 μ m average particle diameter was shocked by the indirect method to produce a quasi-isentropic plane compression wave normal to the cylinder axis. [1]Recovered specimens showed the evidence of melt and possible evaporation . For the lower temperature specimen, compacted structure possibly sintered through melt was observed and for the high temperature shock specimen newly formed triangular plates were observed.

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The shock induced polarization is one model to explain the electromotive force (EMF) originated from the shock compressed material and provides a good explanation of the variation of the current from the sample with time. This model suggests that the dipole polarization is induced at the shock front and decay behind the front with some characteristic long relaxation time. The precise microscopic mechanism is still unknown. The amount of induced polarization generally depends on the shock pressure and the material. We report the shock induced electromotive forces for several phases of 4-methoxybenzylidene-4-n-butylaniline (MBBA) and the strong dependence of the magnitude of EMF on the initial state of this material.

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Thin metallic plate was welded onto a ceramic plate using regulated underwater shock wave. The thin metallic plate was accelerated about 900 m/s by underwater shock wave and collided with ceramic plates, such as the ZrO₂ ceramic plate. Bonding was achieved through intensive deformation at the collision point, but cracks were normally generated in the ceramic plate. The use of a cover plate with the metallic plate and other devices such as momentum traps was effective in eliminating cracks in the AI/ZrO₂ joint.

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Using an explosive welding technique, aluminum plate was welded onto various metallic plates and the interfacial reaction phenomena are discussed. Normally, the interfacial zone showed a high-aluminum content phase which dissolved a small amount of the component of the welded material. It was assumed that an intensive deformation at the collision point was mainly generated within the aluminum. In the case of Al-Ti, the aluminum content was decreased and the composition corresponded with TiAl or Ti₃Al which suggested that the mechanism of the reaction was changed.

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In order to study the stability of converging cylindrical shock waves an annular vertical diaphragmless shock tube was designed and constructed. This shock tube has a self-sustained structure and produces cylindrical shock waves with a wide range of shock Mach numbers and a higher degree of repeatability. Double exposure holographic interferometry method was used for quantitative flow visualization. It is found that the cylindrical shock waves converge more uniformly in this vertical strut-free shock tube than in a former horizontal annular shock tube and behavior of the converging cylindrical shock waves is clarified.

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A simple analytical model is presented to study hydrodynamic perturbation growths induced by nonuniform laser ablation in the start-up phase in laser fusion. Namely, propagation of a rippled shock and deformation of an ablation surface caused by nonuniform laser ablation are studied for cases of initial target roughness and nonuniform laser irradiation. The perturbation growth is very important because it seeds the Rayleigh-Taylor instability in the subsequent acceleration and stagnation phases. In result, it can be shown that high intensity of laser irradiation promotes the ablation surface to distort and short wavelength of laser inhibits its deformation. Those behaviors are also investigated in the case that nonuniformity of laser irradiation oscillates with time.

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Focusing of a toroidal shock wave emitted from a co-axial annular shock tube and the resulting shock wave reflection were studied numerically with a dispersion-controlled scheme. A shock wave discharged from an open-end of a circular shock tube into ambient air was calculated first for comparison with an experimental interferogram. After obtaining good agreement, further three cases were calculated with various initial shock Mach numbers. It was found that intense shock focusing appears when toroidal shock waves merge at the axis of symmetry. A somewhat unusual shock wave reflection was also observed in the case of higher shock Mach numbers.

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Shock compression experiments on Kinosaki basalt (2. 7 g/cm³) was carried out in the interest of collisional phenomena of planetesimals in the early solar nebula. Shock wave attenuation in basalt were examined using in-material manganin and carbon pressure gauge. The shock waves of 7 and 33 GPa in peak pressure attenuated with the attenuation rate of -1. 8 and -1. 6, respectively. Three attenuation effects were considered: rarefaction wave effect, geometrical expansion effect, and energy dissipation effect. In the rarefaction effect, two waves, reflected wave and edge wave, were newly considered. Our result showed that the reflected rarefaction wave and the geometrical expansion effects affected on shock pressure attenuation and that the energy dissipation effect could be regarded negligible small. The attenuation rate was consistent with that of the impact fragment ejection velocity.

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Shock-induced electromotive forces were measured in water and potassium-fluoride aqueous solutions. While we obtain the same result of former researches for pure water, the magnitude of the emf signal tended to increase with concentration in weak aqueous solutions. These phenomena may be explained with the assumption that emf is initiated by the change in Fermi level of measuring electrode under high pressure polarizing the adjacent liquid. The emf signals generated in concentrated solutions behaved unlike those of dilute solutions. Some models are proposed as the source of shock induced emf signals.

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This paper describes results of shock recovery compaction experiments with a diamond / silicon composite powder. Under diamond compaction process, the addition of silicon causes to increase the hardness of recovered specimens. Because additive silicon reacts with diamond accompanying heat generation. This heat process contributes to reduction of micro and macro clack generation. The purpose of this study is to clarify the microstructure in the diamond compacts including silicon, and the effect caused by the addition method of silicon. By transmission electron microscopy (TEM) analysis, the boundary between diamond grains consist of amorphous carbon, graphite, silicon carbide and silicon. Silicon-carbite exist in the amorphous carbon layer as very fine particles.

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The present communication reports Raman spectroscopy in the 193K to 293 K temperature and 0. 1 MPa to 50 GPa pressure range of pure anhydrous and hydrated nitric acid (69 w%). The main result is the autoionisation of pure nitric acid at high pressure.

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Ion-beam driven shock loading device is proposed to make efficient dynamic compaction of nanocrystal and non-equilibrium powders. Different form the conventional gas-guns and powder fire-guns, the repetitive application of shock pressure pulse to targeting materials and the fine control of pressure pulse are intrinsic features to the present approach. Since the generated plasmoid is electro-magnetically accelerated to launch the flyer, no limitation to flyer velocity is present. The laser doppler velocimetry is used to make real time measurement of copper flyer velocity. The efficiency is estimated to be about 6 % for conversion from the accumulated energy in the condenser bank to the kinetic energy of a flyer.

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Behaviors of the diamond formation reactions from graphite carbon source under the excess pressure in a molten metallic solution of carbon is characterized by the appearance of the regrown graphite, and can be optionally controlled by relative thermodynamical stabilities of the source, the regrown graphite and diamond to be formed, which are adjusted by the reaction pressure and its sequential change. Detailed understanding of the growth process in the temperature gradient method leads to an improved geometry of the growth space for an efficient growth. Problem of the growth surface is also discussed from the view points of "sound" growth without entrapping the solvent and incorporation of the solvent-composing elements as impurities dissolved in diamond.

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Homoepitaxial diamond films were grown on (100) natural type Ia diamond anvils using high density microwave plasma enhanced chemical vapor deposition (CVD). The growth morphology of the epitaxial films were compared for substrate temperatures from 1075 to 1365°C and thane precursor concentrations of 1 and 2% in a hydrogen plasma at 90 Torr. The diamond layers were polished to near optical flatness using an industrial grade polycrystalline diamond (PCD) disc attached to a high rpm rotating wheel. Diamond anvils with CVD layers on the tips were tested up to a pressure of 74 GPa without any film deformation. The versatility of the diamond polishing apparatus allows damaged or CVD-grown anvils to be shaped into a beveled-tip geometry for use in ultra-high pressure applications.

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High-quality synthetic type IIa diamond crystals of several carats, containing less than 0. 1 ppm chemical impurities and few inclusions, have been successfully synthesized by the temperature gradient method under high pressure and high temperature. The crystals are transparent over a wide range of wavelengths from ultraviolet to far infrared regions, showing no absorptions due to impurities. They also have high crystalline quality with fewer crystal defects, less internal strain, and less variation in defects among crystals than those of natural diamonds or conventional synthetic type Ib diamond. The outstanding characteristics of the synthetic type IN diamond permit application to a considerably wide range of industrial and scientific uses such as optical parts, monochromators, high-pressure anvils, and so on.

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Transparent platelets of nanocrystalline diamond and amorphous diamond were fabricated successfully from C₆₀ fullerene using a shock compression and rapid quenching technique . The former nanocrystalline diamond platelets consist of a few nanometer-sized crystallites that are unstable in themselves because of higher surface energy . The platelets were transparent and very hard, nearly comparable to type ha diamond. Transmission electron microscopy and electron energy loss spectroscopy revealed that individual crystallites were combined directly or through a very thin and modified sp³ carbon layer, which possibly stabilized the nanometer-sized crystallites. Such nanotexure caused the transparency and hardness of the present material.

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Two sorts of diamond-MgCO₃ compacts with grain sizes of 6∼12μm (mean grain size: 7. 5μm) and 20∼40μm (mean grain size: 23μm) were prepared and examined. The effects of diamond grain size on the amount of MgCO₃ and Knoop hardness were not remarkable. The coarser grained diamond compact with MgCO₃ sintering agent exhibited little better wear resistance than the finer grained one and showed tiny flaking on a rake face and small recession of a cutting edge in a cutting test of granite. When compared with a conventional diamond-Co system, the effects of a sort of a sintering agent on the properties of compacts were much more remarkable than those of diamond grain size. Namely, the diamond-MgCO₃ compacts showed much smaller amount of a sintering agent, higher hardness and better cutting performance for granite, irrespective of grain size.

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New data on the synthesis conditions, structure and physical properties of the superhard and ultrahard samples created from solid C60 by static high-pressure high-temperature treatment in the range of 9. 5-13 GPa ; 600 -2100 K are represented. Measured velocities of the compressional sound waves in the ultrahard fullerites exceed the highest values for diamond. Bulk elastic modulus for the hardest fullerite samples more than twice exceeds that of diamond. Ultrahard fullerite tip is applied for measurements of hardness of diamond and fullerites. Maximum hardness of fullerite is measured to be 310±40 GPa.

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The phase diagram published by Bundy & Wentorf [2] already shows cBN to be the stable fonn of boron nitride, in contrast to similar diagrams used today. This picture is supported by theoretical calculations by Maid et al. [5] and Solozhenko [6]. Results of compressibility measurements for cBN and hBN are presented . To clarify the picture of the phase diagram the transformation from hBN to cBN has been studied in a series of time dependent diffraction experiments using synchrotron radiation. The crystallization is found to go through the melt. In a second series of experiments the back-transformation of cBN to hBN was studied . Finally the experimental conditions for high pressure! high temperature synthesis of cBN could be lowered to 2. 5 GPa at 1800°C using amorphous boron nitride as starting material.

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Growth characteristics of single crystal cubic boron nitride (cBN) grown on a (111) surface of diamond seed crystal was studied. A temperature gradient method was employed by using lithium boron nitride as a solvent under 5. 5 GPa and 1500°C for 10 min to 100 hr. The island nucleation of (111) crystals was taken place even at 10 min. The island crystals were, then, coalesced and the (113) faces were dominantly appeared, followed by (113) faceted growth. Considering the growth rate of the crystal under constant P-T growing condition, the growth of the crystal in this system seemed to be controlled by the interface reaction on the crystal but not by the diffusion of the BN source in the reaction bath.

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We first synthesized a new carbon hard material, a B-C-N heterodiamond of composition BC_{2. 5}N, using an advanced explosive shock compression technique combining extremely high pressure (∼50 GPa), high temperature (3000-10000°C), rapid reaction (∼μs), and rapid quenching. The heterodiamond is a polycrystalline material stuck with microcrystallites of 10 nm in average size. The constituent atoms are all tetrahedrally coordinated to give C-C, C-B, C-N, and B-N bonds. The material has the excellent thermal resistance and bulk modulus in comparison with diamond and cubic BN.

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Super-hard sintered composites in the systems of B₆O-B₄C and B₆O-cBN were prepared by high pressure sintering of composite powders containing in-laboratory synthesized B₆O powder. Nearly fully dense sintered composites were obtained under the high pressure and temperature treatment conditions of 3-6 GPa, 1500-1800°C and 10-30 min. Vickers microhardness of the sintered composites ranged form 3000 to 4600 kg/mm² depending on the composition and sintering conditions. The fracture toughness of the B₆O-cBN system which was higher than that of the B₆O-B₄C system, was observed by the enhanced crack propagation along the grain boundary between B₆O and cBN.

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Using high-pressure-high-temperature treatment of fullerites it is possible to prepare new carbon materials, including polymerized fullerites, amorphous carbon, and nanocrystalline diamond-plus-graphite composites. We have studied the mechanical properties (hardness, Young modulus, fracture toughness coefficient) for some of new phases. The interrelationship between hardness and density, established for the fullerite-based carbon phases, is in good accordance with the corresponding data for amorphous carbon.

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This paper focuses on the properties of sodium azide (NaN₃) and its role in the formation of carbon nitrides. Specifically, our data suggest phase changes in azide induced by high pressures at room temperature. We also present recent results from attempts at carbon nitride synthesis with azide/graphite and azide/diamond combinations raised to pressures and temperatures in a diamond anvil cell. Laser-heated samples are investigated by image plate X-ray diffraction using a synchrotron source.

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Phase relation among h-BN/w-BN/c-BN was observed using cubic anvil apparatus with synchrotron radiation. Starting material was pyrolytic hexagonal boron nitride (p-BN). Above 4. 5GPa, wurtzite phase (w-BN) reported to be stable above 10GPa was appeared at room temperature, while h-BN was unchanged. At temperature above 1000°C, diffraction peaks of c-BN was appeared at pressure higher than 7. 5GPa. Clear temperature dependence of the transition boundary from w-BN to c-BN was not observed. The transition boundary to c-BN lay between 7 . 1 and 7. 5 GPa with no temperature dependence up to 2000°C.

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Diamonds were grown in solvents of Fe-Ni-Co, Ni-Fe-Cr and Ni-Fe-Cr-Ti alloys, and analyzed by the method of x-ray fluorescence using synchrotron radiation as the excitation source. Behavior of Fe, for which dissolution in the diamond lattice has hardly been confirmed, is discussed on the basis of point analyses together with concentrations averaged over the whole sample. It is revealed that Fe is dissolved possibly at a concentration of about 1 ppm or less without showing any preference to the growth sector. Cr is thought to be dissolved more hardly than Fe. Concentrations of Some impurity elements are influenced by the presence of Ti, and Cr as well.

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The sintering behavior of cubic boron nitride (c-BN) composites and c-BN / ceramic whisker composites under conditions in which the c-BN is thermodynamically metastable were studied by HIPing, and by ultrahigh pressure hot isostatic pressing (UHPHIPing), and by ultrahigh pressure hot pressing (UHPHPing). The c-BN fine particles (particle size: 0.5-2μm) coated with TiN by a physical vapor deposition (PVD) method, was used. A high-purity alumina (α-Al₂O₃) powder produced by the ammonium-aluminum carbonate thermal decomposition process were used as bonding materials with a very small amount of magnesia and titania, and 0, 30 and 40vol% SiC whiskers were also added. The obtained c-BN composites including relatively large amount of c-BN, or c-BN and SiC whiskers, were fully compacted without forming h-BN. Some of them showed very high hardness that ranked with c-BN cutting tools.

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In this work it was used the system of four die displacement sensors for anvils clearance measurement with the aim to keep watch on pressure variation in "anvil with hollow" type of high pressure apparatus during diamond synthesis. It was shown that natural direct connection between pressure inside reactive cell and height of deformed gasket exists independently of the cause of pressure change. The special inserts and previously sintered metal-catalyst were used to stabilize the process of diamond single crystals synthesis. Their application allowed to reduce pressure fall in a reactionary cell from 0. 13Gpa/min to 0. 02GPa/min, and also to raise yield of high quality diamond crystals.

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