Low-temperature ceramics of the 3Y-TZP-Al2O3 system, containing sintering additives

In this work, we studied the effect of complex additives containing Na2Si2O5 and Ni, Zn oxides on the properties and sintering temperature of a ceramic material 3Y-TZP- Al2O3 with an aluminum oxide (Al2O3) content of 5 wt %. It was shown that the introduction of complex additives promoted an increase in the flexural strength of ceramic materials. The greatest strength (445±22 МПа) was achieved by sintering at 1250 °C on the composition with 5 wt % Na2Si2O5 and 0.33 mol % Zn.

Effects of SiC On the Microstructure, Densification, Hardness and Wear Performance of TiB2 Ceramic Matrix Composite Consolidated Via Spark Plasma Sintering

Monolithic TiB2 are known to have a good combination of densification and hardness which are sometimes useful but limited in application. However, their usage in service at elevated temperatures such as in power thermal plants, cutting tools, tribological purposes (cutting tools, mechanical seals, blast nozzles, and wheel dressing tools), etc leads to catastrophic failure. Hence, the introduction of sintering additives in the TiB2 matrix has a high influence on the improvement of its sinterability, and properties (fracture toughness, wear resistance etc.,) of the resulting composite needed to meets the requirement for various industrial applications. In this study, the influence of SiC as sintering additives on the microstructure, densification, hardness and wear performance of TiB2 ceramic was observed. Hence, TiB2, TiB2-10wt%SiC and TiB2-20wt%SiC were sintered at 1850 oC for 10 minutes under 50 MPa. The impacts of SiC on the TiB2 were observed to improve the microstructure correspondingly improving densification and mechanical properties, most especially with the composites with 20wt% SiC. Combined excellent densification, hardness and fracture toughness of 99.5%, 25.5 GPa, 4.5 MPa.m1/2 were achieved respectively for TiB2-20wt%SiC. Diverse in-situ phase and microstructural alterations were detected in the sintered composites, and it was discovered that the in-situ phase of TiC serves as the contributing factor to the enhanced features of the composites. Moreover, the coefficient of friction and wear performance outcomes of the synthesized composites described a decrease in the coefficient with an enhanced wear resistance via the increasing SiC particulate, although the application of the load from 10 N-20 N increased the wear rates.

Structure and properties of K0.5Na0.5Nb0.96Sb0.04O3 piezoelectric ceramics doped by CuO

Envisaged through adding sintering additives to achieve low-temperature sintering preparation, in order to overcome the volatilization of sodium ions and potassium ions in the high-temperature preparation, so as to improve the density and electrical properties of KNN-based piezoelectric ceramics. This research uses traditional solid-state sintering technology, a high density, high properties lead-free piezoelectric ceramics, KNNSC-[Formula: see text], successfully prepared with sintering additives CuO. The modern test analysis of XRD and SEM shows that a moderate amount of CuO doped in the range of research can form a single perovskite structure of an orthorhombic structure, not found in any second phase, and can promote grain evenly growing and improve the sintering properties of KNN-based piezoelectric ceramics. The KNNSC-0.04 ceramics exhibit excellent electrical properties through various electrical tests such as [Formula: see text] = 238pC/N, [Formula: see text]= 47%, [Formula: see text]= 1049, tan[Formula: see text]= 2.4%, [Formula: see text] = 25.6 [Formula: see text]C/cm2, [Formula: see text] = 1.24 kV/mm, respectively. These test results show that the KNNSC-[Formula: see text] piezoelectric ceramics have great potential to be applied in middle- and low-voltage piezoelectric devices.

Development of a High-Performance-Ferrite Magnet Fabrication Process without Sintering Additives

Sintered M-type hexaferrites with the chemical formula of Sr0.3Ca0.4La0.3Fe9.8Co0.2-xMnxSi0.135O19-d (x = 0, 0.05, 0.1, 0.2) and Sr0.3Ca0.4La0.3Fe9.8-yCo0.2MnySi0.135O19-d (y = 0.05, 0.1, 0.2) were prepared by conventional solid station reaction routes. A high sintering density of more than 95% of the theoretical density was achieved in all hexaferrite samples when calcination was carried out at 1100 oC for 4 h, followed by sintering at 1230-1250 oC for 2 h without the use of sintering additives. High saturation magnetization and coercivity were achieved simultaneously at the x = 0.05 composition, where Mn replaces part of the Co. The secondary phase Fe2O3 generated by the initial addition of SiO2 was gradually reduced when the Fe contented was decreased in the Sr0.3Ca0.4La0.3Fe9.8-zCo0.15Mn0.05Si0.135O19-d samples, and a single M-type hexaferrite phase was confirmed in the Sr0.3Ca0.4La0.3Fe8.3Co0.15Mn0.05Si0.135O19-d (z = 1.5) sample, which also exhibited optimized hard magnetic properties, with a saturation magnetization of 4581 G and coercivity of 4771 Oe. Anisotropic sintered magnets were fabricated using the optimized composition, and showed excellent hard magnetic properties, with a remanent magnetic flux density of 4400 G and intrinsic coercivity of 4118 Oe, and a maximum energy product of 4.72 M·G·Oe. This result is very promising because high magnet performance can be achieved with a single batch process without the need for sintering additives during the process.

Effects of Composite Sintering Additives: Al(OH)3+Y2O3+CaF2 on the Performance of Porous Mullite Oxide-Bonded SiC Ceramics

A composite sintering additive system: Al(OH)3+Y2O3+CaF2 was proposed for porous mullite oxide-bonded SiC ceramics. Small variations of sintering additives have significant influences on the phase composition, pore shape/size, density and flexural strength. Samples sintered at 1550 ℃ for 4 h in the air atmosphere realized both good mullite densification and no detectable cristobalite phase, which was difficult to be achieved at the same time. Besides, the composite sintering additive system also promoted the formation of columnar shape mullite, which acts as a reinforcement. Flexural strength as high as 108 MPa was achieved at an apparent porosity of 40.3 vol%, which is higher than that sintered by SPS technique. Moreover, those additives also act as pore formers determining the shape and size of pores. Around 8.9 µm strip-like, 11.8 µm continuous channel-like and 4.1 µm irregular pores were obtained for Al(OH)3, Al(OH)3-Y2O3 and Al(OH)3-Y2O3-CaF2 added samples, respectively. Corresponding phase evolution, sintering mechanisms and pore formation models were established. This work provides a simple way to modify the phase, pore size/shape, and strength of mullite oxide-bonded porous SiC ceramics by properly selecting sintering additives without any additional pore formers.