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Various nylon 6-clay hybrids, such as molecular composites of nylon 6 and silicate layers of montmorillonite and saponite, NCH's and NCHP's, respectively, have been synthesized. To estimate the mechanical properties of these hybrids, tensile, flexural, impact, and heat distortion tests were carried out. NCH was found superior in strength and modulus and comparable in impact strength to nylon 6. The heat distortion temperature (HDT) of NCH (montmorillonite: 4.7 wt. %) was 152 °C, which was 87 °C higher than that of nylon 6. In NCHP, saponite had a smaller effect on the increase of these mechanical properties. The modulus and HDT of NCH and NCHP increased with an increase in the amount of clay minerals. It was found that these properties were well described by the contribution of the constrained region calculated from the storage and loss modulus at the glass transition temperature. According to the mixing law on elastic modulus, the following expression was obtained between the modulus E at 120 °C and the fraction of the constrained region C, En = Ecn = C, where the values of n and Ec (modulus of the constrained region) were 0.685 and 1.02 GPa, respectively.

Natural Na-montmorillonite was cation exchanged for the ammonium cations of various ω-amino acids [H3N+(CH2)n−1 COOH, n = 2, 3, 4, 5, 6, 8, 11, 12, and 18]. X-ray diffraction (XRD) results suggested that the chain axes of ω-amino acids with a carbon number of eight or less were parallel to the silicate layers, and that the chain axes of those with a carbon number of 11 or more were slanted to the layers. The cation-exchanged montmorillonites form intercalated compounds with ∊-caprolactam at 25 °C. The montmorillonites intercalated with both ω-amino acid and ∊-caprolactam were studied by XRD measurement at room temperature and 100 °C. We propose a model where amino acid molecules were arranged perpendicular to silicate layers and ∊-caprolactam molecules filled the space between them. When the ∊-caprolactam was melted at 100 °C, the basal spacing for the montmorillonite increased, in which the carbon number exceeds 11. This phenomenon will be applicable to obtaining the nylon 6-clay hybrid, a molecular composite of nylon 6 and montmorillonite.

The understanding of the microfracture mechanism is essential for the im provement of the performance of the materials and the establishment of the quality assurance procedures. In this study, the microfracture mechanism of composite leaf springs produced from unidirectional glass fiber reinforced epoxy resin was studied using acoustic emission technique in combination with in situ failure analysis using SEM. It was found that the fracture mechanism consists of the following two steps: the breakage of in dividual fibers followed by matrix microcracking from the broken fiber tips, and the simultaneous breakage of some tens of fibers accompanied by small delamination failure from the broken tip, leading to final failure. It was found that the mechanical property of the matrix was greatly improved by modifying the epoxy resin, which results in a retarda tion of matrix microcracking from the broken fiber tips. This retardation, confirmed by the acoustic emission measurement and in situ failure analysis, can greatly improve the dura bility of the material. The microfracture mechanism of a prototype composite spring was characterized under flexural loading using the acoustic emission measurement. Based on the result, an optimum geometrical design of the spring to reduce the microfailure was ob tained. During this study, the employment of the acoustic emission technique as a quality assurance test of the spring was assessed. It was found that improperly manufactured springs generate a lot of the emission by loading to a maximum design load, while prop erly manufactured ones hardly generate the emission. It can be concluded that the acoustic emission technique is effective as a quality assurance test for the composite springs.

Compairing the literature values of fracture toughness of various materials revealed that the value of the same kind of material scatters largely, depending on the authors or measuring ways, but that the temperature dependence is very small and almost common, particularly in the range RT through 1, 200 °C, for most ceramics in spite of the large scattering in the absolute value. The temperature coefficient, (-(dKIc/dT)/KIc(RT)), is(-2. 1-1.6)10-5/K for SiC ceramics, and(0-1.3)10-4/K for Si3N4. The unexpectedly small temperature dependence was explained on the basis of the dependence of the surface free energy, rs.which was found to be approximated by the empirical formular (-(dγs/dT)/γso = 1/(2.1Tm) ; Tm is melting or sublimation point ) and that of Young's modulus, E. On this basis, the value of KIc at 1, 600 °C is expected not to be less than 70% of the value at RT, if the material is not affected by low heat resistant boundary material. Furthermore, the literature values are found to be 2 to 6 times larger than the ideal value calculated from (2γsE)1/2. This large value is related to the generation of rough fractured surface.

The microfailure behaviour of thermoplastic polyamide 6,6 composites reinforced with randomly dispersed short glass fibres was studied. Scanning electron microscopy was carried out on the surface of the composites under load to observe directly the behaviour. The microfailure proceeds following the steps (1) interfacial microfailure occurs at the fibre tips, (2) the microfailure propagates along the fibre sides, (3) plastic deformation bands of the matrix occurs from the interfacial one, (4) crack opening occurs in the band and the crack grows slowly through the band, (5) finally a catastrophic crack propagation occurs through the matrix with pulling-out fibres from the matrix. A model for the microfailure mechanism of the composites is proposed and some methods to improve the mechanical properties of the composites are discussed on the basis of the mechanism.

Significance of the constitutional size in the composites having the constitution of nanometer size (Nano-Composites) was emphasized. Every Nano-Composite should have two critical values, the upper limit and the lower limit, for the dimension of the constitution to posses the distinguishable property as Nano-Composite. The critical values depend on the property expected for the composite. The values were estimated or re-viewed on various basis which are thought to be useful for each property, such as cata-lytic activity, magnetism, optical property as well as mechanical one. For examples: The range of the binding force acting across the surface of solids was estimated from the surface free energy and the ideal strength, which gives the critical value in general expression for the constitutional dimension and also for one basic aspect of catalitic activity. The values are about 7 nm(Si3N4), 4 nm(SiC), 4 nm (Al), 2 nm(Fe), 2 nm(W) and 3 nm(Pt). The value is very small for oxides, 0.5 nm(Al2O3) and 0.4 nm(MgO) probably due to screening effect on the surface. As to magnetic properties, 100 mn for super paramagnetism's occurrence and 20 nm for making the originally hard magnetic material soft one. Optically, the value is about 50 nm for reflective intex change. Mechanically, it is about 100 nm for strengthning or restricting dislocation movement. Some improved properties, which could be expected or have been realized, are described in the relation with the critical values.

Originally incompatible blends of SAN 30% and PC 70% were extruded with extremely high shear rate up to 107 s-1 as a typical example of the blends. The.blends are of binary systems microscopically in the first run of extruding, where SAN is present as small spherical particles in PC matrix. The apparent volume fraction of the spherical SAN estimated from the microscopic photographs decreases with the shear rate. The fraction is decreased also with the repeated runs. The blend appears uniform or structureless at the fifth run. Dynamic loss tangent gives two peaks corresponding to T ?? of SAN and PC, respectively. The latter shifts to lower temperatures with the number of extruding run. It is considered that some of SAN is mixed with PC in a compatible form. The pulsed NMR analysis supports the conclusion.

The critical grain size, below which the properties of the composites could be much different from those of the conventional composites, was estimated on the basis of the ideal strength and the specific surface energy. It is about 2nm-4nm for normal metal (Fe, Co), less than 1nm for oxides (Al2O3, MgO), and about 10nm for Si3N4, which suggests Si3N4 is one of the most advantageous materials for Nanometer Composites.

Ideal Strength, aid as a function of temperature was found to be approximated by the following formula:σid≥σid=∫TxT3αE/(1-2μ)dT=3αE(Tx-T)/(1-2μ)where Tx stands for the minimum value of transformation points (melting, sublimation, solid to solid, and brittle to ductile), and α, E, μ respectively for the coefficient of linear thermal expansion, Young's modulus and Poisson's ratio. The formula's error is less than 20%, expressed in the term of error compared with whisker's strength at RT. It was also compared with literature data on high temperature strength of sapphire monofilament, which proved the compatibility of the formula.σid is estimated as 9 GPa for SiC and 3.5 GPa for Si3N4 at 1, 400°C, 1 GPa at 2, 200°C for SiC, and 1 GPa at 1, 700°C for Si3N4. These values prove the usefulness of the materials as high temperature gas turbine components. The formula tells also us that the ideal strength can be well approximated by a straight line regardless of material.The Young's modulus plotted against temperature can be converted to Young's modulus plotted against strain, e, by using e=3∫α/(1-2μ)dT, which can not be given directly from experimental measurement due to the occurrence of fracture in the material. The tangent of the curve for MgO was proved to agree well with the value given by a classical solid state theory. The range of binding force acting across material surface was estimated by using the ideal strength, giving 0.5-1 nm for SiC and Si3N4 and 0.1-0.5 nm for MgO and Al2O3. The allowable atomic distance difference between neighboring layerd material in coherently multilayered films, which has no defect was also estimated to be less than 3% from the ideal fracture strain.

C-cut sapphire was implanted with 400 keV Co+ ions to doses of 3 × 1017/cm2 and 5 × 1017/cm2 and then annealed in air sequentially at 1273, 1373, and 1473 K. Before and after the annealing, the implanted surfaces were examined by RBS and XRD methods. A nearly homogeneous layer of 350 nm thickness was formed on the surface when sapphire was implanted to a dose of 5 × 1017/cm2 and then annealed at 1473 K. For sapphire implanted to a dose of 3 × 1017/cm2 and then annealed at 1473 K, the implanted layer had a complex structure: the top surface layer of 70 nm thickness was α-alumina with Co3+ ions at the substitutional sites and the near-surface layer (70 nm–300 nm) was a mixed phase of CoAl2O4 and α-alumina.

By introduction of ionicity into Lindemann's one-phase theory on melting temperature, a semi-empirical formula for melting temperature of simple compounds, $$T_m \doteqdot {{f_i C_i } \mathord{\left/ {\vphantom {{f_i C_i } {r_{AB} }}} \right. \kern-\nulldelimiterspace} {r_{AB} }} + {{f_c C_c } \mathord{\left/ {\vphantom {{f_c C_c } {r_{AB^{2.5} } }}} \right. \kern-\nulldelimiterspace} {r_{AB^{2.5} } }}$$ has been given, whereTm,fi,fc andrAB stand for melting temperature, ionicity, covalency and bonding distance, respectively.Ci andCc are numerical factors which are common to a group of compounds of similar character (crystal structure, valency, etc). Application of Sanderson's ionicity scale to the formula shows good agreement with the observed melting temperatures of alkali halides. A good agreement is also obtained for single oxides. From application of the formula to alkali halides, it is suggested that an anion plays an important role in melting. Similarity ofCi andCc in alkali halides of NaCl structure and MO-type oxides of the same structure suggests that melting occurs at almost the same critical position in Lindemann's model for melting in both types of compound.

In the present study, we investigated deposition of diamond films on both Si substrates pre-treated with diamond powder by an ultrasonic vibrator and also further ion-implanted. The pre-treatment with diamond powders increased a density of diamond nucleation on Si substrate by five-order of magnitude against to the untreated substrate. 280keV Ar+ ion implantation at 90K to the pre-treated substrate significantly reduced the density of the diamond nucleation while the implantation at 773K scarcely affected the density. It is proposed that healing of micro-flaws, which are thought to work as the nucleation sites, is an important mechanism to reduce the diamond nucleation density by ion implantation.

Influence of fiber diameter on the mechanical properties of short fiber composite was studied by using smaller diameter fibers than conventional ones. Strength and toughness of the composite reinforced with the small diameter fibers were improved, compared to those of the composite reinforced with the conventional ones, except for extremely small diameter fibers. Thus, there exists the maximum value for the strength and toughness for the optimum fiber diameter. This result indicates that there is an optimum condition for the reinforcing effectiveness by the small diameter fibers. In order to analyze the reinforc ing mechanism by the small diameter fibers, fracture mechanism of the composite was studied by an acoustic emission analysis, in-situ SEM observation of failure process, and observation of plastic deformation of the matrix. As a result, initiation and propagation of microcracks occurring at fiber/matrix interface were found to be strongly suppressed by using the small diameter fibers, compared with those in the conventional composite. A model for explaining the reinforcing mechanism by the small diameter fibers was pro posed, which can well explain the presence of the optimum fiber diameter, resulting in the highest reinforcing effectiveness for the composite.

Masao Kohzaki, Shoji Noda. Haruo Doi and Osami Kamigaito : Improvement of The Tribological Properties of Ceramics by Si Film Deposition and Ion Irradiation.We studied the tribological properties of surface modified SiC ceramics with a pin-on-disk friction and wear tester in an ambient atmosphere without oil lubrication. The friction coefficient between Si film deposited SiC(Si/SiC) and a diamond pin was about 0.05, which was smaller than one half of that between SiC and a diamond pin. The low friction state of Si/SiC lasted for 40 hours when the Si/SiC was irradiated with Ar+ ions. Ar+ ion irradiation was also effective for reducing the wear. Effectively no wear was detected in Si/SiC irradiated to the dose over 5 × 1015 ions/cm2.

Methods of estimating Weibull parameters by omission of some data in a sample are considered for various functions for survival probability in linear Weibull plots. Computer simulation is used for the consideration. A use of the survival probability function, (P(i) = 1 − (i − 0.5)N, in whichP(i) is survival probability,i is thei-th order of failure strength andN is the total number of data in the sample, and the omission of 2 to 4% of the data, which are of the smallest value, the largest one and their neighbours, are recommended to get the best value of the Weibull parameters.

Silicon nitride ceramics were implanted with 200 KeV Cr+ ions and then oxidized at temperatures from 1273 to 1473 K in air. The oxidation scales were examined by RBS, XRD and SEM methods. At temperatures up to 1373 K, in the Cr+-implanted ceramics, the implanted Cr atoms were predominantly oxidized to Cr2O3, which resulted in a reduction of the oxidation of Si4N4 to SiO2, and then the diffusion of impurity cations through the grain boundary to the surface oxide (SiO2) was also retarded. For the oxidation at 1473 K, there was little difference in oxidation behavior between the implanted specimen and the unimplanted one. But the preoxidation at 1273 K of the implanted specimen was found to give the implanted specimen a little better resistivity against the oxidation at 1473 K.

Crystalline phase transformation from α-phase to ω-phase(high pressure phase) was found to occur in Zr thin film on sapphire when it was irradiated with N+ or Ar+ions at low temperature. Ion irradiation at ambient temperature caused only grain growth of the α-phase. The ω-phase formation is tentatively attributed to crystal growth in collision cascade under large compressive stress which was generated by preceding irradiation.

Sapphire plates whose strength was degraded previously by Vickers indentation were irradiated with 300 keV Ni+ or 400 keV Mn+ ions, and the strength recovery was studied as a function of ion dose. Also the strength degradation by Vickers indentation in sapphire plates irradiated previously with 400 keV Mn+ ions to the dose of 5×1017 ions/cm2 was studied to evaluate the resistivity to the crack initiation due to point contact stresses.The strength of sapphire plates which were degraded previously to about 50% of the original strength was recovered to about 90% of the original strength of the sapphire by Ni+ or Mn+ ions irradiation of the dose of 5×1017 ions/cm2.The crack initiation by Vickers indentation was largely retarded by ion irradiation to the sapphire specimen. The retardation was attributed to the presence of amorphous layer made by Mn+ ions irradiation.

Characteristic acoustic emission behavior was observed when a composite was subject to a thermal cycle (thermo-acoustic emission). A lot of emission was observed in the ther mal cycle for a composite which had damage induced by mechanical loading. On the other hand, the emission was hardly observed for a sound composite in the thermal cycle. The occurrence of the emission was restricted only to the composite with damage. Further more, the emission activity depended on the degree of the damage. The emission is con sidered to be generated due to the friction of the crack faces by the thermal loading. The thermo-acoustic emission measurement is considered to be anticipated as nondestructive evaluation for composite materials.

A prediction of fatigue life and fracture stress of ceramics of a heterogeneous system was made by application of fracture mechanics based on slow crack growth. It was shown that the prediction of fatigue life and fracture stress in ceramics of heterogeneous system in general could be dealt with in a similar way to those of ceramics of a homogeneous system. Experimental examination of the validity of the prediction was made with LAS glass ceramics (Li2O-Al2O3-SiO2) at various stages of devitrification as well as foamed glass. These results proved the validity of the formulae derived.

Fiber orientation induced during injection mold filling of fiber filled thermoplastics causes material properties to be anisotropic and molded parts to warp. Predicting fiber orientation is important for parts and mold designs to produce sound molded parts. A computer program has been developed to predict planar fiber orientation in thin walled molded parts by using Folgar and Tucker's orientation model for concentrated suspensions. Computed result was compared with experimental one for an injection molded square plate of glass fiber reinforced polypropylene.

Single-crystal alumina was implanted firstly with 400 keV Si+ and subsequently with N2+ ions and then annealed at 1673 K in an No atmosphre. The implanted layers were characterized by means of X-ray diffraction, Rutherford backscattering-channelling of 2 MeV He+ ions, and the resonance nuclear reaction15N(p,αγ)12C. The annealing of sapphire implanted at ambient temperature resulted in the formation ofβ′-sialon, a solid solution ofβ-silicon nitride and alumina in the subsurface layer, while implantation at ≈ 100 K resulted in the formation of aluminium oxynitride in the surface layer. In the latter case, the implanted silicon atoms were believed not to react vxi1h the implanted nitrogen atoms but with the substrate oxygen atoms. These crystalline precipitates were found to have epitaxial relations with the sapphire substrate.

400KeV Ag+ ions were irradiated to the (100) surfaces of 9.5m% Y2O3 stabilized ZrO2 with the doses ranging from 5×1015 ions/cm2 to 5×1017 ions /cm2 at room temperature in order to investigate the correlations between the state of implanted Ag and the suppression of crack initiation.1) Ag precipitated as particles in orienting the (200) face of Ag. The sizes of the Ag particles were ranging from 2nm(5×1016ions/cm2)to 11nm (5×1017ions/cm2).2) Knoop hardness of the surface of ZrO2 increased by about 20-30% by Ag+ ion-irradiation at the doses less than 5×1016ions/cm2 and decreased at the doses larger than 1×1017ions/cm2.3) Vickers indentation crack at a loads of 0.25N was completely suppressed in the surface of ZrO2 irradiated to a dose of 5×1017ions/cm2.4) The suppression of the crack initiation may be ascribed to the influence of the nanometer composite layer containing max. 23at% Ag.

The object of this study was to investigate the fracture mechanism of unidirectional carbon-fibre reinforced epoxy resin composite. For this purpose, the failure process of the composite under load was observedin situ by scanning electron microscopy and the matrix deformation around the broken fibre tip was examined by polarized transmission optical microscopy using a thin section of the composite. The failure process was shown to proceed through the following four stages: (1) fibre breakage began to occur at a load of about 60% of the failure load; (2) as the applied load was increased, plastic deformation occurred first from the broken fibre tip along the fibre sides, followed by final matrix cracking in the plastic region; (3) just before failure, partial delamination occurred, originating from fibre breakage and matrix cracking; (4) finally, a catastrophic crack propagation occurred from the delamination, leading to composite failure. Acoustic emission monitoring was also carried out for non-destructive evaluation, which indicated that internal failure began to occur at a load of 60% of the failure load and propagated remarkably before composite failure. A close correspondence between the acoustic signal and crack formation was obtained. The acoustic signal at lower amplitude, occurring over whole load range, corresponded to fibre breakage and matrix cracking while that at higher amplitude, occurring only just before failure, corresponded to partial delamination. From these experimental studies, the fracture mechanism of the composite has been clarified.

The mechanism of fracture of short glass fibre-reinforced polyamide 6.6 thermoplastic was studied by means of optical and electron microscopy and acoustic emission methods. It was found that there were three stages in the failure, i.e. initiation of the interfacial cracks at fibre ends, propagation of the interfacial cracks along fibre sides, and propagation of the crack into the matrix leading to the failure of the composite. On the fracture surface, fibres were almost pulled-out from the matrix, not broken. The close correspondence between the crack initiation and propagation and the amplitude of AE signals was observed. The AE signals of lower amplitude occurring under a relatively low stress were considered to be made in association with the initiation and propagation of the interfacial cracks. The AE signals of higher amplitude observed prior to the failure of the composite were considered to be made in association with the occurrence of the matrix cracks. Furthermore, in order to analyse the effect of the stress state in the composite on crack occurrence and propagation, the stress levels in matrix, fibre and interface were estimated for the composite stressed to the failure stress. The calculation was based on the equivalent inclusion method proposed by Eshelby and on an assumption of a perfect bond between the matrix and the fibres. The result was found to be consistent with the mechanism of the fracture, the occurrence of the interfacial cracking in the initial stage and the matrix cracking in the final one.

Thermal fatigue life of ceramics under mechanical load was studied using a soda-lime-silica glass rod. The life was also calculated by the application of fracture mechanics of ceramics based on slow crack growth. Both results agreed well. For instance, the following formulae hold well for the fatigue life of the ceramics under mechanical stress: $$\begin{gathered} ln ( - ln P)\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{ \doteq } \frac{m}{n}ln N + \frac{{lm}}{n}ln \sigma _{M O} + \frac{{(n - l)m}}{n}ln (\Delta T) + C' \hfill \\ \frac{l}{{(n - l)}} \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{ \doteq } \frac{{\sigma _{M O} }}{{\sigma _{T O} }} \hfill \\ \end{gathered} $$ whereP,N,σTO,σMO, δT,m,n/C′ are survival probability, thermal stressing cycles (thermal fatigue life), the maximum thermal stress, mechanical stress, thermal shock severity, Weibull modulus, a material constant and constants, respectively. By the application of the second formula, the thermal stress induced on the glass rod in plunging the rod into water from hot atmosphere was estimated. The estimated value (11.2 kg mm−2 for a glass rod of 4mm diameter and δT=180° C) is thought to agree rather well with that estimated from the well-known formula derived from heat diffusion theory (9.7 ~ 15.8 kg mm−2) considering the accuracy of the approximation.

Flow analysis has been studied in plastic injection molding. It can predict defects in the filling process with computer. The computer simulation has been used for mold design. This paper describes mold filling theory and our experience with a flow analysis program, "IMAP-F".

Sapphire plates, cut parallel to an {0001} plane, have been implanted with 300 keV nickel ions to doses ranging from 5×1012 to 1×1017 Ni cm−2 at specimen temperatures of 100, 300 and 523 K, in order to investigate the effect of implantation temperature on the mechanical property changes in sapphire caused by ion implantation. The measured changes in surface hardness, surface fracture toughness and bulk flexural strength were found to depend strongly on the implantation temperature, and were largely correlated with the residual surface compressive stress measured by using a cantilever beam technique. The surface amorphization that occurred only by the implantation at 100 K and at doses larger than ∼2×10s15 Ni cm−2 reduced the hardness to ∼0.6 relative to the value of the unimplanted sapphire, and considerably increased the surface plasticity. Furthermore, the amorphization was found to involve a large volume expansion of ∼30% and to change drastically the apparent shape and size of a Knoop indentation flaw made prior to implantation. This effect was suggested to reduce stress concentrations at surface flaws and hence to increase the flexural strength.

Formula to estimate the ideal strength of brittle material was derived from the consideration of the relationship between the fracture under uniform tensile stress and the transformations of the material, sublimation, melting and solid to solid transformation. The validity of the formula was examined by comparing the ideal strength with the fracture stress of whiskers. The accuracy of the formula was within ± 30% for the material whose ionicity is less than 50%. The fracture stress of the whisker whose ionicity is more than 50% is about 1/3 to 1/5 of the value given by the formula. The discrepancy in the ionic materials seems to come from the possible occurence of shear fracture in the materials. From the formula, mullite is concluded that it would have the fracture stress similar to silicon nitride.

Energy absorbability of foamed rigid materials, polyurethane and glass, was studied under a compressive load. The brittle materials were proved to absorb much energy in a manner similar to ductile materials. A mechanism for such high energy absorption was proposed, based on a fracture model in which crushing of cells initiates at the weakest cell followed by propagation to cells lying in the layer containing the weakest one and lying in a direction perpendicular to the compressive force; then the crushing propagates to another layer under the compressive force after the completion of the first layer crushing. In the period of one layer crushing, the strain energy stored in the period of compression prior to the crushing is temporarily released, and it is stored again in the period of compression after the crushing. The store and release of strain energy is assumed to be repeated until all cell layers are crushed. This mechanism of layer-by-layer crushing allows the cells to absorb strain energy repeatedly, and causes high energy absorption in the brittle foamed material. The calculated energy based on the mechanism agrees well with the observed one.

SiC ceramics, with and without niobium metal film (Nb/SiC) and Ar + ion-irradiated Nb/SiC were subjected to a pin-on-disk friction-and-wear test with a diamond pin for 40 h. The metal film deposition reduced the friction coefficient and the wear, and no wear found in the irradiated Nb/SiC.

Interface of N+ion-irradiated Zr/SiO2 was examined by the XPS method combined with Ar+ion sputteretching. The ion irradiation was found to form a diffusion layer at the interface and to generate chemical bonds like Zr-Si and Zr-O-Si in the diffusion layer. The diffusion layer was inferred to be an atomically mixed phase of Zr, Si, O, and N atoms rather than a mixed phase of Zr and SiO2.

On the assumption that the thermal fatigue life of ceramics is determined mainly by the duration over which a crack reaches a small critical length, a prediction of the life was made by application of fracture mechanics to ceramics based on subcritical crack growth. Approximated formulae, such asN/N′≃(ΔT N′ /ΔT N ) n , were derived, whereN andN′ are the lives for temperature differences of ΔT N and ΔT N′ , respectively, andn is a material constant. Experimental examination showed that the formulae proved to be valid for glass, sintered mullite under moderate shock severity, and zirconia. Data given by other authors also prove their validity. The deviation of the life from the formulae for sintered mullite under a thermal shock of extremely low severity, suggests that a certain mechanism, for example strengthening, is needed to understand the life of the sintered mullite. Moreover,n determined from the thermal shock experiments is comparable with that given in data determined by a mechanical method.

SiC ceramics, the one deposited with niobium metal film (Nb/SiC) and Ar+ ion-irradiated Nb/SiC were subjected to a pin-on-disk friction and wear test in an ambient atmosphere with a diamond pin for 40 hours. The friction coefficient between SiC and diamond pin was about 0.1. The Nb film deposition reduced the friction coefficient and it was about 0.04 with the normal load of 1000 gf. The wear of SiC was also reduced to one seventh by the Nb deposition. The Ar+ ion-irradiated Nb/SiC was found to have very high wear resistivity and effectively no wear was detected in the samples irradiated to the doses over 5×1015 ions/cm2.

The interface of the Zr/sapphire implanted with N+ ions were examined by RBS and cross-sectional TEM observations. The ion implantation induced the interdiffusion of atoms at the interface and the clear border-line between the Zr film and sapphire was found to disappear. The thickness of the diffusion layer was estimated to be about 10 nm at the interface of the Zr/sapphire implanted with N+ ions to the dose of 2×1017/cm2.

It was found that montmorillonite cation exchanged for 12-aminolauric acid (12-montmorillonite) was swollen by ∊-caprolactam to form a new intercalated compound. Caprolactam was polymerized in the interlayer of montmorillonite, a layer silicate, yielding a nylon 6-clay hybrid (NCH). The silicate layers of montmorillonite were uniformly dispersed in nylon 6. The carboxyl end groups of 12-aminolauric acid in 12-montmorillonite initiated polymerization of ∊-caprolactam, and as 12-montmorillonite content became larger, the molecular weight of nylon was reduced. From the result of end-group analysis, carboxyl end groups were more than amino end groups. The difference between the carboxyl and the amino end groups was attributed to ammonium cations (-NH3+) of nylon molecules, because the difference agreed with the anion site concentration of the montmorillonite in NCH. It is suggested that the ammonium cations in nylon 6 interact with the anions in montmorillonite.