羟基磷灰石生物陶瓷的成型研究

在适宜的条件下，用化学沉淀法合成羟基磷灰石，加以不同粘合剂，并通过干压使其成型，控制不同温度将其烧结成陶瓷。简单分析烧结温度、时间及粘合剂等对HAP陶瓷成型的影响。结果表明：1100℃和3h是HAP生物陶瓷较佳的烧结温度和烧结恒温时间；比较之下，聚乙烯醇对HAP的干压成型工艺较适宜。     

氮化硅/羟基磷灰石复合材料的制备研究

主要用超声分散结合滴定工艺制备了氮化硅／羟基磷灰石(Si3N4/HAp)复合粉体，并经冷压成型、冷等静压成型及无压烧结制备了氮化硅／羟基磷灰石复合材料。X射线衍射(XRD)及扫描电镜(SEM)研究发现，氮化硅的加入促进了羟基磷灰石的分解，细化了晶粒，可降低羟基磷灰石的烧结温度。     

羟基磷灰石的制备、X-ray衍射表征和成型工艺探讨

以沉淀法合成羟基磷灰石（简称HAP）粉末，对生坯进行单向干压成型，设计正交实验，探讨了各主要因素（烧结温度、烧结保温时间和粘结剂）对成型过程的影响。实验结果可知HAP粉末成型的最佳条件为：烧结温度1100℃．烧结保温时间3小时，粘结剂为聚乙烯醇。     

玻璃渗透氧化锆全瓷牙科修复材料的制备与性能表征

采用泥浆法和干压法成型多孔氧化锆陶瓷坯体,经玻璃渗透制备了玻璃氧化锆复合材料,研究了陶瓷坯体的成型和渗透,并对渗透复合材料的性能进行了表征. 结果表明,使用泥浆法成型,氧化锆浆料的固相含量可以达到75%(w),预烧结温度降低至1200℃,坯体预烧结过程中坯体的线收缩率小于0.5%,达到"净成型"要求,3 mm的渗透距离可以在15 min内完成,材料弯曲强度为285 MPa. 使用干压法成型,预烧温度1450℃,收缩率较大,2 mm渗透距离需2 h以上,材料弯曲强度达到400 MPa. 两种方法分别适用于泥浆直接成型工艺和CAD/CAM切削加工,所制复合材料可用于牙冠的核心瓷.     

磷酸盐玻璃渗透3Y-TZP全瓷齿科材料的研究

将3Y-TZP粉体经过干压成型和1250℃无压烧结,得到了可切削性能良好、孔隙率适中的多孔3Y-TZP陶瓷基体.配制了磷酸盐玻璃,经过烧结、急冷、粉碎后得到了成分为48.0％ P2O5、25.0％ CaO、10.0％ B2O3、6.0％Al2O3、6.0％ Li2O、3.0％ ZrO2和2.0％ Y2O3的玻璃粉料,玻璃粉料在1100℃渗透温度下具有合适的粘度、良好的渗透性和化学相容性,且平均热膨胀系数与陶瓷基体匹配.在磷酸盐玻璃中引入氧化钇后,渗透多孔3Y-TZP后形成陶瓷/玻璃渗透复合体中,氧化锆以四方相为主,没有发生明显相变.陶瓷/玻璃渗透复合体的弯曲强度和断裂韧性分别达到了380.4 MPa和5.40 MPa·m1/2,且渗透过程中收缩率低于0.1％,达到近“净尺寸”成型标准.     

制备工艺对La2O3掺杂氧化镁陶瓷性能的影响

以高纯氧化镁粉体为主要原料,分别掺杂0、2%、4%、6%以及8%（w）的La₂O₃粉体,选用聚乙烯醇为结合剂,研究单轴压成型、等静压成型及不同煅烧温度（1 400、1 500以及1 600℃）对La₂O₃掺杂氧化镁陶瓷烧结性能、显微结构及抗热震性能的影响。结果表明：采用等静压成型,氧化镁粉体受到来自各方向大小一致的成型压力,并均匀地传递至各个方向,从而得到了更为致密的坯体,显著提高了氧化镁陶瓷的烧结性能。提高烧成温度,更有利于掺杂物La₂O₃与MgO形成置换型固溶体或发生晶格畸变,促进烧结,达到致密化。煅烧温度为1 600℃,La₂O₃掺杂量为4%（w）时,经等静压成型坯体最为致密,热震后裂纹细小。这是由于方镁石晶相间交界处的La₂O₃晶体改变了裂纹走向,阻挡和分散了部分能量和应力,减缓了裂纹的线性延伸。     

R2O-Al2O3-B2O3-SiO2系统玻璃对羟基磷灰石的烧结及其相转变的影响

系统地研究了R2O－Al2O3-B2O3-SiO2系统玻璃对羟基磷灰石（HAP，Hydroxyapatite)的烧结和相转变的影响。其中玻璃组成为Na2O5-12,K2O 7-15,Al2O3 3-5,ZnO 0-5,B2O3 15-25,SiO2 65-75(wt%).结果表明R2O－Al2O3-B2O3-SiO2系统玻璃有较强的促进HAP烧结能力，但在较高温度下会促使HAP分解；合适的添加量为30wt%，烧结温度为1000℃。     

天然羟基磷灰石生物陶瓷的制备及性能表征

用兽骨经过焚烧得到天然羟基磷灰石,采用超细粉碎法制备了亚微米羟基磷灰石粉体,进行了制备工艺的优化,同时结合SEM,XRD等分析测试手段对获得的粉体进行了组分、颗粒尺度分布和微观形态分析。采用固相烧结技术制备天然羟基磷灰石生物陶瓷,确定了烧结工艺参数,即烧结温度在1250℃,成型剂的最佳添加量为6%,烧结时间4h。测得其陶瓷样品的烧失率为3.19%,密度为3.04g·cm-3。利用X-射线衍射和扫描电子显微电镜（SEM）对生物陶瓷样品的晶相组成和形貌进行了表征。     

溶胶-凝胶法引入烧结助剂制备SiC-Y3Al5O12复相陶瓷

以碳化硅、六水硝酸钇、九水硝酸铝和六次甲基四胺为主要原料,通过溶胶-凝胶法引入Al2O3和Y2O3复合烧结助剂,液相烧结制备得到SiC-Y3Al5O12(Y3Al5O12简称YAG)复相陶瓷.采用DTA、TEM、XRD等分析测试技术研究了溶胶-凝胶法引入复合烧结助剂过程及复合烧结助剂对SiC-YAG陶瓷的烧结性能、力学性能、物相组成与显微结构的影响.结果表明干凝胶在920℃左右已完全转变成YAG相,最终获得的YAG粒径小,并均匀分散在SiC表面的SiC-YAG复合粉体;复合粉体先干压、再等静压成型后,在1860℃下烧结45 min,所制得复相陶瓷的相对密度达到了96.5%,抗弯强度达到486 MPa,断裂韧性达到5.7 MPa·m1/2.     

Gd_(0.98)LuTb_(0.02)O_3透明陶瓷的真空烧结和光学性能

利用燃烧法制备得到了Gd0.9BLuTb0.02O3纳米陶瓷粉体.在不加任何添加剂和烧结助剂的情况下,粉体采用干压和等静压成型.研究了烧结温度和烧结时间对陶瓷的致密化和晶粒长大过程的影响.在此研究的基础上调整烧结制度,于1 750℃真窄烧结6h制备得到了Gd0.98LuTb0.02O3透明陶瓷.厚度为0.2mm的透明陶瓷在可见光区的透过率高于70%,相对密度达到99.8%.该透明陶瓷在X射线激发下发射出黄绿光,发射主峰位于540nm,对应于Tb3+的5D4→7F5跃迁.     

炭黑分散度检测标准GB/T 18251应用过程中遇到的问题浅析

主要对GB/T 18251—2019《聚烯烃管材、管件和混合料中颜料或炭黑分散度的测定》标准中给出的炭黑分散度检测过程中试样厚度范围、厚度测量方法及切片法中试样形状、试样幅宽、试样制备过程中遇到的问题做了讨论研究。试样厚度是制备试样的一个重要参数,标准中未给出具体测量方法,应予以补充,建议采用显微镜测量法。标准中给出的炭黑分散度试样厚度范围（20±10）μm不合适,实际检测过程中发现能用于试验的试样厚度小于10μm。标准中未给出切片法制备试样的形状和幅宽,建议使用正方形试样,幅宽4 mm,切片过程中可能会遇到无法切到指定厚度范围的试样,可以采用低温冷冻后再切样的办法解决。     

Hot pressing sintering of zinc sulfide microsphere decorated with nanorods synthesized by the simple refluxing method

A zinc sulfide microsphere decorated with nanorods was synthesized using the refluxing method. Then, the as-obtained ZnS nanostructures were consolidated via the hot pressing (HP) technique. X-ray diffraction, Fourier transforms infrared spectroscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy, and X-ray mapping analyzes were used to characterize the ZnS sample. The effects of various factors such as pH, temperature, and reaction time were investigated on the morphology and particle size of ZnS nanostructures. The formation of sphalerite phase of ZnS nanoparticles was confirmed by the XRD analysis. FESEM also revealed that ZnS nanostructures with the molar ratio 1:1.3 (zinc: sulfur) had a spherical morphology decorated with sulfur nanorods. The ZnS nanostructures were consolidated by hot pressing technique at 860 °C for 2h under vacuum atmosphere. XRD analysis indicated that the sintered ceramic had a sphalerite phase. FESEM study demonstrated that ZnS ceramic had a grain size diameter within the range of 1–3 μm.     

等静压成型熔融石英陶瓷的研究

介绍了等静压成型熔融石英陶瓷的技术,研究了水分含量、粒径分布、粘合剂的加入量及烧成温度对制品的成型性能、体积密度、弯曲强度和显气孔率等性能的影响.结果表明:当水分含量在0.3%～1.0%(质量分数)之间,粒径分布为双峰分布,PVA加入量为1.5%,最高烧成温度为1250 ℃时,能成功制备出性能优异的熔融石英陶瓷天线罩.     

等静压成型碳化硅多孔陶瓷

介绍了等静压成型碳化硅多孔陶瓷的制备技术,研究了高温结合剂加入量及成型粘合剂的加入量对制品的成型性能、气孔率、孔结构、强度等性能的影响.     

Cu-SiC磨具制备及其性能表征

笔者描述了铜-碳化硅磨具的制备过程,采用热压成形法制备了Cu-SiC磨具。该磨具主要由铜粉、酚醛环氧树脂和碳化硅磨料组成。研究了树脂、碳化硅与辅助磨料的种类、组成对磨具性能的影响。结果表明:当加入适量铜粉,复合材料磨损率会下降、耐磨性能会提高,被磨削表面不易出现凹痕、孔洞;但是铜粉添加过量时,磨具磨损率会增加。较佳配方组成为:35wt%树脂、45wt%碳化硅、15.56wt%铜粉、4.44wt%白刚玉。     

Synergetic effects of SiC and Csf in ZrB2-based ceramic composites. Part II: Grain growth

The synergetic effects SiC particles and short carbon fibers (C_sf) as well as hot pressing parameters (sintering temperature, dwell time and applied pressure) on the grain growth of ZrB₂-based composites were investigated. Taguchi methodology was employed for the design of experiments to study the microstructure and grain growth of ZrB₂–SiC–C_sf ceramic composites. Three hot pressing parameters and SiC/C_sf ratio were selected as the scrutinized variables. The sintering temperature and SiC/C_sf ratio were identified by ANOVA as the most effective variables on the gain growth of ZrB₂-based samples. Removal of oxide impurities from the surface of starting particles by the reactant C_sf, not only hindered the extraordinary grain growth of ZrB₂ matrix, but also improved the sinterability of the ceramics. A fully dense ceramic with an average grain size of 8.3 µm was obtained by hot pressing at 1850 °C for 30 min under 16 MPa through adding 20 vol% SiC and 10 vol% C_sf to the ZrB₂ matrix. SEM observations and EDS analysis verified the in-situ formation of ZrC which can restrain the growth of ZrB₂ particles, similar to the role of SiC, by the pinning of grain boundaries as another stationary secondary phase.     

自蔓延高温合成/快速加压法制备二硼化钛陶瓷的致密化机理

用自蔓延高温合成/快速加压(self-propagating high temperacre synthesis/quick pressing,SHS/QP)法制备了 TiB2陶瓷.用扫描电镜及透射电镜观察陶瓷产品的微观形貌.对TiB2陶瓷致密化的动力学过程及结构形成过程进行了分析,并提出SHS/QP陶瓷烧结的致密化机理.结果表明:在SHS/QP过程中TiB2陶瓷的致密化是晶粒的重排及高温塑性变形共同作用的结果.     

Effect of yttria substitution on structure,optical and mechanical properties of (Gd,Y)2O3–MgO nanocomposite ceramics

A citrate-nitrate combustion method was applied to synthesize fine composite Gd_2-xY_xO₃-MgO (x = 0, 0.02, 0.2, 0.3, 0.4, 0.6) nanopowders. Y₂O₃ substitution inhibited Gd₂O₃ phase transition from cubic structure to monoclinic structure during sintering, thereby stabilizing its cubic structure to room temperature. This approach led to nanocomposite ceramics with a grain size of about 190 nm and increased the transmittance to 85% over the 3–5 μm wavelength range when x = 0.3. However, the addition of Y₂O₃ weakened the mechanic properties of the nanocomposite ceramics.     

Fabrication of transparent MgAl2O4 ceramics by gelcasting and cold isostatic pressing

Highly transparent MgAl₂O₄ ceramics have been fabricated by aqueous gelcasting combined with cold isostatic pressing (CIP), pressureless sintering and hot isostatic pressing (HIP) from high purity spinel nanopowders. The gelling system used AM and MABM as monomer and gelling agent. The influences of dispersant and PH on the rheological behavior of the MgAl₂O₄ slurries were investigated. The spinel slurry with low solids loading (25 vol%) and low viscosity (0.15 Pa s) was obtained by using 6 wt% Duramax-3005 (D-3005) as dispersant. After CIP, the green body had a relative density of 48% with a narrow pore size distribution. The influence of sintering temperature on densification and microstructure was studied, choosing 1500 °C as the sintering temperature. After HIP (1650 °C/177 MPa/5 h), transparent MgAl₂O₄ ceramic with the thickness of 3 mm was obtained, whose in-line transmittance was 86.4% at 1064 nm and 79.8% at 400 nm, respectively. The ceramic exhibited a dense microstructure with the average grain size of 23 μm. The Vickers hardness and flexure strength of the sample reached 13.6 GPa and 214 MPa, respectively.