成型压力对氧化铝瓷球性能的影响

研究了成型压力对瓷球烧结、密度及耐磨性的影响。结果表明：在本研究系统内随着压力的增加,瓷球的烧结温度下降,烧成温度范围拓宽。采用150MPa成型的瓷球的密度最大且耐磨性最好。     

不同铝含量瓷球的烧结及性能比较

分别以铝含量为50％、60％、70％、80％并配以等量的烧结助熔剂来制造氧化铝瓷球。研究了不同铝含量对瓷球密度、烧结、以及对瓷球耐磨性的影响。结果表明，瓷球的密度随铝含量的增加而增大；Al(60％)瓷球烧结温度较低，Al(70％)瓷球烧结温度较高；Al(60％)瓷球磨损率相对较低，Al(80％)瓷球磨损率最高。     

CaO-MgO比例对中高铝瓷球性能的影响

保持AI2O3和si02含量不变,变化CaO和MgO的比例制造氧化铝瓷球。研究了不同CaO、MgO含量对瓷球密度、烧结以及耐磨性的影响。结果表明,随着CaO含量降低、MgO含量的升高,瓷球烧成温度升高,密度相近,但磨耗降低。     

氧化锆增韧氧化铝耐磨瓷球的研制

以煅烧种分法所得氢氧化铝超细粉制取的特种α-氧化铝超细粉为主要原料,试验研究了ZTA耐磨瓷球的生产工艺及特性。结果表明:①在平均粒径1～1.5μm的上述α-氧化铝超细粉中添加18～20％的Y—PSZ,经造粒、等静压成型后,于1650℃下烧制1小时,其相对烧结密度达98.8％,磨耗率为0.036％/hr,仅为通常氧化铝95瓷球的1/5～1/8;②加入MnO_2、TiO_2等烧结助剂可适当降低烧成温度、提高烧结密度,但不利于提高ZTA瓷球的耐磨性。     

成型方法对用辊棒废料制备的瓷球性能的影响

分别采用等静压成型与手搓成型工艺制造氧化铝瓷球；研究表明不同的成型方法不仅对瓷球的烧成及物理性能有影响，且对其磨损规律有着很大的影响；等静压成型瓷球的烧结温度较手搓成型瓷球要低，硬度及密度比手搓成型瓷球要高；手搓成型瓷球的磨损率随时间增加而增加，等静压成型瓷球的磨损率随时间增加而相应减小。     

影响95氧化铝瓷球耐磨性的几个关键因素

本文介绍了影响９５氧化铝瓷球耐磨性的几个关键因素,并指出氧化铝瓷球原料配方中使用辅助原料引入ＣａＯ、ＭｇＯ,对降低烧结温度,提高耐生的益处。     

中铝瓷球的应用研究

本文以长石、粘土、矾土等天然矿物原料,采用可塑法成型工艺,研究了配方与烧结温度、瓷球密度、外观颜色的关系,研制成功了成本低、密度大、外观质量较好的中铝瓷球的较佳配方,并解决了瓷球生产中的关键工艺技术问题。     

工艺条件对用辊棒废料制备的中铝瓷球显微结构及性能的影响

以辊棒废料为主要原料,在CaO-MgO-SiO2-Al2O3体系中,研究烧结温度、保温时间、成型方式和压力大小对中铝瓷球显微结构及性能的影响规律及其机理.结果表明:在150MPa等静压成型,1330oC烧结,保温3h的工艺条件下,研制含铝量小于60%的中铝瓷球的性能最优异,磨损率为0.0503%/h,密度为3.1062g/cm3,与市售90瓷球相比,磨损率与之持平,白度与市售90瓷球不相上下.     

氧化铝瓷球的成形方法及设备简介

１前言 随着建陶行业的不断发展,天然球石的产量和性能已不能满足需要,势必要有一种人工球石来代替,氧化铝瓷球是较好的替代品,可根据不同要求选择不同档次的氧化铝瓷球,因而对氧化铝瓷球的需求量越来越大,档次也越来越高。本文将就氧化铝瓷球的几种生产方法及其设备作一简要介绍。２氧化铝瓷球的生产方法及其设备２．１挤压法成形氧化铝瓷球 挤压法成形氧化铝瓷球是目前同类瓷球中档次最低,但也是产量最大的一种成形方法,一般用于成形中铝以下瓷球或者是粘土球。这种瓷球烧结温度低,生产设备简单,投资小,只需要有球磨机、压滤机…     

用辊棒废料制备中铝瓷球的烧结机理研究

以辊棒废料为主要原料，在CaO-BaO-SiO2-Al2O3体系中，采用常压低温烧结工艺，研制出含铝量小于60％的高性能中铝瓷球，其磨损率为0．0507％／h，密度为3．1082g／cm^3，与市售90瓷球相比，磨损率与之持平，白度与市售90瓷球不相上下，通过XRD和SEM分析，研究用辊棒废料制备中铝瓷球的烧结机理及其工艺条件对烧结的影响。     

Influence of sintering pressure on the microstructure and tribological properties of low temperature fast sintered hot-pressed Y-TZP

Contrarily to conventional sintering (CS) method where longer cycles and high temperature (1400–1500?°C) are applied to sinter yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics, this work presents a faster and low temperature (1175?°C) way through hot pressing (HP) to produce full densified zirconia with good mechanical and tribological properties. This work is concerned with the influence of sintering pressure on the microstructure and tribological properties of hot-pressed Y-TZP. For this purpose, four sintering pressures 5, 20, 60 and 100?MPa were tested. The wear tests were carried out by reciprocating ball-on-plate as a simplified test for tooth-to-restorative material contact under 37?°C using artificial saliva to mimic oral conditions. The results demonstrated that density, hardness and tribological properties are strongly influenced by the sintering pressure, namely an improvement with pressure increase was achieved. The highest density, hardness values and wear resistance were achieved for Y-TZP samples produced at P?=?100?MPa. Furthermore, it was revealed that a smaller grain size for Z100 samples (full densification condition) was achieved comparatively to conventional-sintered Y-TZP. This work proves that it is possible to produce dense Y-TZP materials under low sintering temperature and faster cycles with reduced grain size without compromise mechanical and tribological properties.     

烧结制度对二钛酸钡陶瓷性能的影响研究

二钛酸钡具有优异的介电性能和铁电性能,作为无铅无铋新型的绿色环保材料在动态随机存储器、非挥发铁电存储器等方向将具有广阔的发展空间。本文讨论了烧结致密化对其物相组成及微观形貌的影响。结果表明:在1200℃以内,随烧结温度的升高,晶粒趋于均匀,气孔率下降,致密化程度提高。随烧结压力的升高,试样的相对密度逐渐提高,说明提高烧结压力可有效改善BaTi₂O₅陶瓷的烧结程度。50MPa时,试样的致密度达到最大值86.70%,可基本满足制备薄膜靶材的使用要求。     

Densification and enhancement of SiC particulate-reinforced fine-grain SiC ceramic

Dense sintering of SiC nanopowder under low temperature and pressure remains a big challenge, because of the great resistance caused by the severe agglomeration of nanopowder. A novel sintering strategy is proposed to prepare SiC composite ceramics by sintering the mixture of SiC nanopowder and SiC micron powder at low temperature and pressure. The SiC micron powder was in the size of 100 µm with little sintering activity, which was designed as a pressure conductor to promote the densification of SiC nanopowder. Experimental results showed that the SiC micron powder had a significant effect on increasing of the sintering density of nanopowder and improving the mechanical properties of SiC ceramics. An SiC composite ceramic with a relative density of 98%, a Vickers hardness of 22.6 GPa, and a fracture toughness of 5.43 MPa m^1/2 could be sintered by spark plasma sintering under 1700°C and 30 MPa by adding 30 wt.% 100 µm SiC micron powder as reinforcements.     

Sintering highly dense ultra-high temperature ceramics with suppressed grain growth

Grain coarsening normally occurs at the final stage of sintering, resulting in trapped pores within grains, which deteriorates the density and the performance of ceramics, especially for ultra-high temperature ceramics (UHTCs). Here, we propose to sinter this class of ceramics in a specific temperature range and coupled with a relatively high pressure. The retarded grain boundary migration and pressure-enhanced diffusion ensure the proceeding of densification even at final stage. A highly dense TaC ceramic (98.6 %) with the average grain size of 1.48 μm was prepared under 250 MPa via high pressure spark plasma sintering using a C_f/C die at 1850 °C. It was suggested that the final-stage densification is mainly attributed to grain boundary plastic deformation-involved mechanisms. Compared to the usual sintering route using a high temperature (>2000 °C) and normal pressure (<100 MPa), this work provides a useful strategy to acquire highly dense and fine-grained UHTCs.     

A novel technique for the development of acetabular cup by cold isostatic compaction and sintering of UHMWPE powder with optimized processing parameters

Life of a metal on ultra-high molecular weight polyethylene (UHMWPE) total hip replacement is often limited to 10–15 years, due to wear loss and aseptic loosening. Due to its high melt flow index, UHMWPE is typically processed by ram extrusion or compression molding technique, but yet to be processed to the full potential of its mechanical integrity in acetabular shape without any fusion defects or weak bonding. The main objective of the present study is to develop a novel technique to fabricate defect-free acetabular cups with desired bearing characteristics and surface finish by sintering medical-grade UHMWPE GUR 1050 powder after its cold isostatic compaction with optimum processing parameters. Sintering kinetics of UHMWPE is studied comprehensively using a thermomechanical analyzer. The influence of compaction pressure, sintering temperature, and sintering duration on sintering kinetics of UHMWPE is explored to realize their optimum. The optimally processed UHMWPE has the relative density of 97% and Vickers hardness of 5.4 with tensile yield strength and elastic modulus of 21.5 and 625 MPa, respectively. The newly developed acetabular cup exhibited inherent plateau-finished bearing surface with an average surface roughness of <100 nm, having good bearing characteristics and desired dimension.     

Optimisation of the spark plasma sintering process for high volume fraction SiCp/Al composites by orthogonal experimental design

Based on orthogonal experimental design (OED), the effects of the sintering pressure, sintering temperature and holding time on the mechanical properties of 50 vol% silicon carbide particle (SiCp)/2024Al composites prepared by spark plasma sintering (SPS) were investigated. The sintering pressure had the greatest effect on the density and bending strength of the material among these three factors, followed by sintering temperature and holding time. The optimised process conditions for producing the 50 vol% SiCp/2024Al were sintering at 550 °C for 5 min under 40 MPa, which resulted in a composite material with a density of 99.7% and good interface bonding with a comparatively high bending strength of 766.65 MPa. This work provides a promising method to produce high volume fraction composites that can meet high strength requirements.     

Influence of processing parameters on the densification and the microstructure of pure zinc oxide ceramics prepared by spark plasma sintering

Due to the sensitivity of nanopowders and the challenges in controlling the grain size and the density during the sintering of ceramics, a systematic study was proposed to evaluate the densification and the microstructure of ZnO ceramics using spark plasma sintering technique. Commercially available ZnO powder was dried and sintered at various parameters (temperature (400–900?°C), pressure (250–850?MPa), atmosphere (Air/Vacuum) etc.). High pressure sintering is desirable for maintaining the nanostructure, though it brings a difficulty in obtaining a fully dense ceramic. Whereas, increasing the temperature from 600 to 900?°C results in fully densified ceramics of about 99% which shows to have big impact on the grain size. However, a high relative density of 92% is obtained at a temperature as low as 400?°C under a pressure of 850?MPa. The application of pressure during the holding time seems to lower the grain size as compared to ceramics pressed during initial stage (room temperature).     

冷等静压成型压力对反应烧结氮化硅陶瓷性能的影响

将硅粉冷等静压成型,通过反应烧结得到氮化硅陶瓷,研究了成型压力对反应烧结氮化硅(RBSN)陶瓷性能的影响。结果表明,当成型压力从100MPa增加到300MPa,反应烧结氮化增重率逐渐下降,从60.25%降到47.31%;而残余硅含量随着增加,从10%增加到29%;RBSN开气孔率随着成型压力的增大而减小,开气孔率从20.50%降到13.81%。成型压力小于等于200MPa时,RBSN的密度和强度随成型压力的增大而增大;成型压力大于200MPa时,RBSN的密度随成型压力的增大而减小,强度随成型压力的增大变化不大,变化约为5%;在200MPa时,RBSN的密度达到最大值2.52 g/cm3。冷等静压成型RBSN由晶须状α-Si3N4,柱状β-Si3N4和残余硅组成。