共查询到20条相似文献,搜索用时 15 毫秒
1.
Extremely strong diffusion bonds can be made directly between Y2 O3 -stabilized TZP ZrO2 and Fe─18Cr─8Ni stainless steel above a critical joining temperature of about 1100°C. Fracture initiates at the metal/ceramic interface with plasticity occurring in the metal. Bonding is accompanied by a thin interfacial reaction layer which may possibly lead to local melting during the bonding cycle. This behavior is similar to that observed with Ni─Cr alloys bonded to TZP ZrO2 , but a less vigorous interfacial reaction occurs with stainless steel, and stronger bonds can be made. 相似文献
2.
S. JILL GLASS PATRICK S. NICHOLSON C. BURTON CLARK A. H. HEUER 《Journal of the American Ceramic Society》1985,68(7):176-C
The interfacial reaction between Y2 O3 -partially-stabilized ZrO2 and α-Al2 O3 was studied. It was noted that α-Al2 O3 forms inside the periphery of the β-Al2 O3 grains; its formation suggests the loss of Na2 O from the p-Al2 O3 , either by evaporation or by dissolution in the ZrO2 matrix. The presence of Na2 ZrO3 is suspected. 相似文献
3.
Mikio Fukuhara 《Journal of the American Ceramic Society》1989,72(2):236-242
The effect of Al2 O3 and (Ti or Si)C additions on various properties of a (Y)TZP (yttria-stabilized tetragonal zirconia polycrystal)–Al2 O3 –(Ti or Si)C ternary composite ceramic were investigated for developing a zirconia-based ceramic stronger than SiC at high temperatures. Adding Al2 O3 to (Y)TZP improved transverse rupture strength and hardness but decreased fracture toughness. This binary composite ceramic revealed a rapid loss of strength with increasing temperature. Adding TiC to the binary ceramic suppressed the decrease in strength at temperatures above 1573 K. The residual tensile stress induced by the differential thermal expansion between ZrO2 and TiC therefore must have inhibited the t - → m -ZrO2 martensitic transformation. It was concluded that a continuous skeleton of TiC prevented grain-boundary sliding between ZrO2 and Al2 O3 . In contrast, for the ternary material containing β-SiC in place of TiC, the strength decreased substantially with increasing temperature because of incomplete formation of the SiC skeleton. 相似文献
4.
Andreja Gajovi Kreimir Furi Svetozar Musi Igor Djerdj Antun Tonejc Anelka M. Tonejc Dangsheng Su Robert Schlögl 《Journal of the American Ceramic Society》2006,89(7):2196-2205
High-energy ball milling initiates a solid-state reaction in an equimolar mixture of TiO2 and ZrO2 . The first stage of ball milling induced the transformation of anatase TiO2 to high-pressure phase TiO2 (II), isostructural with ZrTiO4 . The formation of solid solutions monoclinic ZrO2 /TiO2 and TiO2 (II)/ZrO2 was observed in the intermediate stage. Afterward, a nanosized ZrTiO4 phase was formed in the milled product from the TiO2 (II)/ZrO2 solid solution. The sintering of the milled product at a temperature <1100°C was examined in situ by Raman spectroscopy. The full solid-state reaction toward ZrTiO4 ceramic is completed at a temperature considerably lower than reported in the literature. 相似文献
5.
Seiichi Suenaga Masako Nakahashi Miho Maruyama Takayuki Fukasawa 《Journal of the American Ceramic Society》1997,80(2):439-444
Wetting and brazing studies of sputtering-deposited, submicrometer thin film filler metal in an Ag—Cu—Ti/Al2 O3 system were performed. The interfacial reaction layer between the filler metal and Al2 O3 was investigated. It is possible to make a brazing joint even with a reaction layer of less than 100 nm thickness. Different types of interfacial reaction layers were observed when the Ti content in the filler metal was varied. The Cu—Ti—O system compounds were observed in the samples with high wetting capabilities, but not in the sample with low wetting characteristics. It was found that these compounds are substances that promote effective brazing. 相似文献
6.
Composite ceramic materials based on Si3 N4 and ZrO2 stabilized by 3 mol% Y2 O3 have been formed using aluminum isopropoxide as a precursor for the Al2 O3 sintering aid. Densification was carred out by hot-pressing at temperatures in the range 1650° to 1800°C, and the resulting micro-structures were related to mechanical properties as well as to oxidation behavior at 1200°C. Densification at the higher temperatures resulted in a fibrous morphology of the Si3 N4 matrix with consequent high room-temperature toughness and strength. Decomposition of the ZrO2 grains below the oxidized surface during oxidation introduced radial stresses in the subscalar region, and from the oxidation experiments it is suggested that the ZrO2 incorporated some N during densification. 相似文献
7.
PAUL F. BECKER 《Journal of the American Ceramic Society》1981,64(1):37-39
The initial strength of (σi ) and thermal shock resistances (Δ Tc and σr /σi ), as determined by quench tests, of Al2 O3 -ZrO2 composites are increased by increasing amounts of tetragonal ZrO2 second phase for contents of up to ∼15 vol%. For composites with ≤9 vol% ZrO2 the increases in σr and Δ Tc reflect the increase in γIC with addition of ZrO2 However, for ZrO2 contents >9 vol%, the thermal shock resistances (Δ Tc and σr /σi ) and σi are also affected by machining-induced microcracking in the surface of the samples. For ZrO2 contents >14 vol%, bulk microcracking can become extensive and result in a degradation of σi and Δ Tc . 相似文献
8.
Koji Tsukuma 《Journal of the American Ceramic Society》2000,83(12):3219-3221
Composites of β-Ce2 O3 ·11Al2 O3 and tetragonal ZrO2 were fabricated by a reductive atmosphere sintering of mixed powders of CeO2 , ZrO2 (2 mol% Y2 O3 ), and Al2 O3 . The composites had microstructures composed of elongated grains of β-Ce2 O3 ·11Al2 O3 in a Y-TZP matrix. The β-Ce2 O3 ·11Al2 O3 decomposed to α-Al2 O3 and CeO2 by annealing at 1500°C for 1 h in oxygen. The elongated single grain of β-Ce2 O3 ·11Al2 O3 divided into several grains of α-Al2 O3 and ZrO2 doped with Y2 O3 and CeO2 . High-temperature bending strength of the oxygen-annealed α-Al2 O3 composite was comparable to the β-Ce2 O3 ·11Al2 O3 composite before annealing. 相似文献
9.
Several unusual microstructural features, i.e., 90° tetragonal ZrO2 twins containing antiphase domain boundaries, tetragonal ZrO2 precipitates in a colony morphology, and precipitate-free zones at the perimeter of cubic ZrO2 grains containing fine tetragonal ZrO2 precipitates, were observed in a single ZrO2 -12 wt% Y2 O2 ceramic annealed at 1550°, 1400°, and 1250°C, respectively. The type of phase transformation responsible for each microstructural feature is described. 相似文献
10.
S. P. KRAUS-LANTERI T. E. MITCHELL A. H. HEUER 《Journal of the American Ceramic Society》1986,69(3):256-258
High-resolution electron microscopy was used to image incoherent ZrO2 /Al2 O3 interfaces in ZrO2 -toughened Al2 O3 containing intragranular ZrO2 . These particles are generally spherical but are sometimes faceted. High-resolution electron micrographs provide atomic-level information on the interfacial structure. For spherical particles, both ledgelike images and misfit dislocation-like images accommodated the lattice misfit, depending on the orientation of the interface, while faceted particles imply at least one low-energy ZrO2 /Al2 O3 interface. 相似文献
11.
Xinzhang Zhou Vijay Shukla W. Roger Cannon Bernard H. Kear 《Journal of the American Ceramic Society》2003,86(8):1415-1420
Rapidly solidified ZrO2 (Y2 O3 )–Al2 O3 powders were prepared by melting fine-particle aggregates in a high-enthalpy plasma flame and then rapidly quenching them in cold water or on a copper chill plate. To ensure complete melting and homogenization of all the particles before quenching, the water-quenching treatment was often repeated two or even three times. The resulting melt-quenched powders and splats displayed a variety of metastable structures, depending on composition and cooling rate. ZrO2 -rich material developed an extended solid solution phase, whereas eutectic material formed a nanofibrous or amorphous structure. Under high cooling rate conditions, the ZrO2 -rich material developed a nanocomposite structure ( t -ZrO2 +α-Al2 O) directly by melt-quenching, whereas, more typically, such a structure was developed only after postannealing of the as-quenched metastable material. 相似文献
12.
SABURO HORI MASAHIRO YOSHIMURA SHIGEYUKI SMIYA 《Journal of the American Ceramic Society》1986,69(3):169-172
The fracture toughness of fine-grained undoped ZrO2 -toughened Al2 O3 (ZTA) was essentially unchanged by postsintering hot isostatic pressing and increased monotonically with ZrO2 additions up to 25 wt%. The strength of ZTA with 5 to 15 wt% tetragonal ZrO2 , which depended monotonically on the amount of ZrO2 present before hot isostatic pressing, was increased by pressing but became almost constant between 5 and 15 wt% ZrO2 addition. The strength appeared to be controlled by pores before pressing and by surface flaws after pressing; the size of flaws after pressing increased with ZrO2 content. The strength of ZTA containing mostly monoclinic ZrO2 (20 to 25 wt%) remained almost constant despite the noticeable density increase upon hot isostatic pressing because the strength was controlled by preexisting microcracks whose extent did not change on postsintering pressing. These strength-toughness relations in sintered and isostatically hot-pressed ZTA are explained on the basis of R -curve behavior. The importance of the contribution of microcracks to the toughness of ZTA is emphasized. 相似文献
13.
J. LLorca José Y. Pastor Pedro Poza José I. Peña Isabel de Francisco Angel Larrea Victor M. Orera 《Journal of the American Ceramic Society》2004,87(4):633-639
The effect of Y2 O3 content on the flexure strength of melt-grown Al2 O3 –ZrO2 eutectics was studied in a temperature range of 25°–1427°C. The processing conditions were carefully controlled to obtain a constant microstructure independent of Y2 O3 content. The rod microstructure was made up of alternating bands of fine and coarse dispersions of irregular ZrO2 platelets oriented along the growth axis and embedded in the continuous Al2 O3 matrix. The highest flexure strength at ambient temperature was found in the material with 3 mol% Y2 O3 in relation to ZrO2 (Y2 O3 ). Higher Y2 O3 content did not substantially modify the mechanical response; however, materials with 0.5 mol% presented a significant degradation in the flexure strength because of the presence of large defects. They were nucleated at the Al2 O3 –ZrO2 interface during the martensitic transformation of ZrO2 on cooling and propagated into the Al2 O3 matrix driven by the tensile residual stresses generated by the transformation. The material with 3 mol% Y2 O3 retained 80% of the flexure strength at 1427°C, whereas the mechanical properties of the eutectic with 0.5 mol% Y2 O3 dropped rapidly with temperature as a result of extensive microcracking. 相似文献
14.
Fred J. Parker 《Journal of the American Ceramic Society》1990,73(4):929-932
The characterization and properties of ceramic composites containing the phases Al2 TiO5 , ZrTiO4 , and ZrO2 are described. The range of compositions investigated gives very low average thermal expansions (α24–1000°C as low as −2.0 × 10−6 °C−1 ) and excellent high-temperature stability. The low thermal expansions are apparently due to a combination of microcracking by the titanate phases and a contractive phase transformation by the ZrO2 . The crystal chemistry and microstructure of the product are processing dependent. Although the composites represent a complex microcracking system, the low thermal expansions and high-temperature stability make them potential candidates for commercial applications requiring thermal shock resistance. 相似文献
15.
The crystallization of MgO-Al2 O3 -SiO2 -ZrO2 glasses at 1000°C was studied. Isothermal heat treatments of a cordierite-based glass (2MgO.2Al2 O3 .5SiO2 = Mg2 Al4 Si5 O18 ) with 7 wt% ZrO2 produced surface crystallization of α-cordierite and tetragonal ZrO2 ( t -ZrO2 ). These phases advanced into the glass by cocrystallization of t -ZrO2 rods in an α-cordierite matrix with a well-defined orientation relation. The t -ZrO2 rods were unstable with respect to diffusional breakup (a Rayleigh instability) and decomposed into rows of aligned ellipsoidal and spheroidal particles. The t -ZrO2 was very resistant to transformation to monoclinic symmetry. With a similar glass containing 15 wt% ZrO2 , surface crystallization of α-cordierite and t -ZrO2 was accompanied by internal crystallization of t -ZrO2 dendrites. Transformation of the dendrites to mono-clinic symmetry was observed under some conditions. 相似文献
16.
Koji Tsukuma Kuniyoshi Ueda Kenichi Matsushita Masahiko Shimada 《Journal of the American Ceramic Society》1985,68(2):56-C-
The temperature dependence of bending strength, fracture toughness, and Young's modulus of composite materials fabricated in the ZrO2 (Y2 O3 )-Al2 O3 system were examined. The addition of A1203 enhanced the high-temperature strength. Isostatically hot-pressed, 60 wt% ZrO2 (2 mol% Y2 O3 )/40 wt% Al2 O3 exhibited an extremely high strength, 1000 MPa, at 1000°C. 相似文献
17.
Pure Ba2 Ti9 O20 (BT29) was synthesized by a solid-state reaction in one step with various amounts of ZrO2 powder additive. The transformation kinetics of BT29 were investigated by quantitative X-ray diffractometry (XRD). The results show that stoichiometric powder mixtures transform to the BT29 phase by nucleation and growth mechanism between 1200° and 1300°C with 1.0 mol% ZrO2. The activation energy of the transformation was found to be 620±60 kJ/mol, but decreases to 515±30 kJ/mol when doped with 1.0 mol% ZrO2 . The addition of ZrO2 possibly changes the phase transformation mechanism of BT29 from diffusion controlled to interface controlled. 相似文献
18.
Xue-Ning Huang Chu Kun Kuo Patrick S. Nicholson 《Journal of the American Ceramic Society》1995,78(4):892-896
An epitaxial β-alumina crystal growth method was used to modify α-AI2 O3 platelet surfaces before inclusion as a reinforcing phase in partially stabilized zirconia (3Y-TZP). The as-grown surface phase was Na-β"-AI2 O3 . This was converted to Ca-β"-AI2 O3 by ion exchange, as the latter is more temperature-stable at composite sintering temperatures. The conditions of formation, thermal stability, and chemical compatibility of these interfacial phases were examined. α-AI2 O3 platelets with Ca-β"-AI2 O3 film were incorporated into 3Y-TZP. The β"-AI2 O3 /ZrO2 interface was found to promote platelet debonding and pullout, thus enhancing the α-AI2 O3 platelet/crack interactions during the fracture process. 相似文献
19.
The transformation of ultrafine powders (particle size, 0.01 to 0.04 μm) of the system ZrO2– Al2 O3 , prepared by spraying their corresponding nitrate solutions into an inductively coupled plasma (ICP) of ultrahigh temperature, was investigated. The powders were composed of metastable tetragonal ZrO2 ( mt- ZrO2 ) and γ-Al2 O3 . On heating, the mt- ZrO2 (or tetragonal ZrO2 , t -ZrO2 ) was retained up to 1200°C. At 1380°C the transformation to monoclinic ZrO2 ( m -ZrO2 ) occurred and the amount of the m -ZrO2 decreased with the increase in Al2 O3 content, thus indicating the stabilization of the t -ZrO2 by the Al2 O3 , which seems to be explained in terms of the retardation of grain growth. 相似文献
20.
L. M. Peng 《Journal of the American Ceramic Society》2007,90(4):1312-1314
A layered ternary carbide phase, Ti3 AlC2 , was synthesized by hot pressing from the starting materials of Ti, aluminum, and activated carbon at 1400°C for 2 h. Its composites were also fabricated through addition of micro-sized SiC and partially stabilized zirconia particulates to the pulverized Ti3 AlC2 powders. The polycrystalline Ti3 AlC2 ceramic obtained has a flexural strength of 172 MPa and a fracture toughness of 4.6 MPa·m1/2 , respectively. This compound is relatively soft (Vikers hardness of 2.7 GPa) and exhibits good electrical conductivity with an electrical resistivity of 8.2 μΩ·m. Both the Ti3 AlC2 /SiC and Ti3 AlC2 /ZrO2 composites are superior to the monolithic Ti3 AlC2 ceramic in strength, fracture toughness, and micro-hardness. 相似文献