钛铁矿原位碳热还原合成TiC/Fe复合材料的研究

以天然矿物钛铁矿（FeTiO3)、C（石墨）为原料,采用原位碳热还原法,实现合成与烧结一体化,真空烧结制备TiC/Fe复合材料,探索了一条低成本合成高性能TiC/Fe复合材料的新途径,对反应的热力学过程进行理论分析和实验研究,分析了产物的结构、组织和性能。研究表明：反应产物主要存在两组,即TiC相和Fe的固溶相,球形的TiC颗粒相被包围在网状结构的Fe及Fe合金粘结相中,TiC颗粒尺寸均匀,大小约2－5μm。Mo的加入可以改善金属相对TiC的润湿性。产物中有少量游离碳存在。     

不同种类碳源对TiC–TiB_2复合粉末合成的影响

以二氧化钛、硼酸和不同碳源(炭黑、蔗糖、葡萄糖)为原料,用碳热还原法合成了TiC–TiB_2复合粉末。研究了不同种类碳源及反应温度对TiC–TiB_2复合粉末的影响。用X-射线衍射仪、激光粒度分析仪和扫描电子显微镜对样品的物相组成、晶粒尺寸及颗粒形貌进行了分析。结果表明:以炭黑、葡萄糖为碳源合成TiC–TiB_2复合粉末的适宜宜条件为在1400℃保温2h;以蔗糖为碳源合成TiC–TiB_2复合粉末的适宜条件为在1350℃保温2h。在最适宜反应温度下,以炭黑为碳源合成的TiC–TiB_2复合粉末样品粒径最小,且颗粒之间相互团聚较少,大部分颗粒尺寸在100nm左右。     

钛硅沸石的研究现状及工业化前景

简要地介绍了直接法钛硅沸石的合成。重点讨论了间接法合成的进展及骨架钛、非骨架钛、沸石晶粒大小、催化剂粒度、反应条件对反应性能的影响。为实现钛硅沸石的工业化，应重视开发用廉价原料的直接合成和间接合成技术。     

Ti(C0.12 N0.88)粉末的高温合成

本文研究了以TiC和TiN粉末为原料，通过高温反应直接合成Ti(C0.12 N0.88）。实验表明，按设定组成的摩尔比TiC/TiN等12/88，在1500℃，Ar气氛下恒温5小时，能直接反应合成Ti(C0.12 N0.88）粉末。     

合成柠檬酸三丁酯的催化剂综述

高效催化剂的选择是以柠檬酸与正丁醇为原料合成增塑剂柠檬酸三丁酯的关键环节,文章对柠檬酸三丁酯合成过程中所使用的不同种类催化剂性能、合成影响因素、催化效果、研究进展进行了综合评述,并对催化剂的研究前景进行了展望。     

超细NaY分子筛的合成

在没有添加剂的条件下,研究了以工业级水玻璃为原料原位水热合成超细NaY分子筛,并采用XRD、TEM、BET等方法对所合成的分子筛进行了表征.考察了陈化时间、碱度、晶化时间、晶化温度对NaY分子筛结晶度和晶粒大小的影响.结果表明:在陈化时间64h、硅铝胶组成x为6.0、晶化时间4h、晶化温度100℃的优化条件下,合成了晶粒尺寸小于200 nm的NaY分子筛.     

Al-TiO2-C体系热力学分析及Al2O3-TiC复相陶瓷的燃烧合成

对Al-TiO2-C燃烧合成体系进行了热力学计算,并利用Al-O-N、Ti-O-N、C-O-N三个体系的叠加优势区相图分析了该燃烧合成体系的平衡产物相.结果表明,Al-TiO2-C燃烧合成体系的绝热燃烧温度为2398 K,燃烧合成平衡相为Al2O3和TiC.XRD检测结果与热力学分析结果相吻合,说明该燃烧合成反应进行得较为彻底,证实热力学分析结果可信.原位生成的Al2O3和TiC两相分布较均匀,燃烧合成产物疏松多孔,易于通过球磨方式达到破碎、磨细的目的.     

原位合成TiC/CuTi复合材料的显微分析

将短碳纤维、铜粉、钛粉混合均匀后装模加压制备了TiC/CuTi复合材料,并利用SEM和EDS方法对样品进行显微分析.实验结果表明:Cu粉、Ti粉与碳纤维高温反应能够原位合成TiC,生成的TiC晶粒与CuTi合金润湿性良好.当Ti/C摩尔比达到1.6时,提高Ti粉和碳纤维总的占比含量,生成的TiC晶粒变大.     

锆钒蓝色料固相法合成工艺的研究

系统地研究了原料的种类和组成，矿化剂的选择，烧成制度等工艺要素对固相法合成锆钒蓝色料质量的影响，采用XRD、DTA-TG和激光颗粒分析等测试方法对实验结果进行了分析和讨论，得出一些有益的结论。     

JNT系列干法脱硫综述

0前言 在合成氨、炼油制氢和合成甲醇等过程中，烃类转化、低温变换、甲烷化和氨合成、甲醇合成等中所用催化剂都对“硫毒”很敏感，因此必须首先对原料气进行脱硫。原料气的种类很多，不同原料气含硫情况也不一样，在选择干法脱硫时要区别对待。干法脱硫剂按其性质可分为三种类型：     

真空原位合成SiC-TiC复合粉末及其氧化性能研究

以碳化硅、二氧化钛和炭黑为原料,在真空条件下原位合成SiC-TiC复合粉末。采用XRD、SEM等测试手段对合成SiC-TiC复合粉末的物相组成和显微形貌进行表征,同时对合成的粉末样品的氧化性能进行探讨。实验结果表明:在本实验条件下,SiC-TiC复合粉末适宜的合成条件为在1350℃保温1h。在SiC粉末中原位生成的TiC,以粒径为0.1～0.2μm左右的小颗粒存在。SiC-TiC复合粉末在氧化过程中,在较低温度下TiC优先氧化生成TiO2,在较高温度下(1100℃左右)SiC才开始氧化生成SiO2。     

微波合成纳米碳化钛粉体的动力学研究

以纳米二氧化钛和碳黑为原料，用微波加热合成纳米碳化钛粉体。对微波合成纳米碳化钛的反应过程进行动力学研究。用X-射线衍射法表征合成粉体的合成率及颗粒大小。结果表明，微波合成纳米碳化钛粉体的化学反应属零级反应，且确定了反应动力学方程及反应的活化能。     

C-B4C-SiC与Ti组分的原位反应及热压烧结

以炭黑、炭纤维、Ｂ４Ｃ、ＳｉＣ、Ｓｉ、ＴｉＯ２和ＴｉＣ为原料制备了不同ＴｉＯ２和ＴｉＣ含量的炭／陶复合材料,采用原位合成及热压技术研究了不同ＴｉＯ２和ＴｉＣ含量对多组分炭／陶复合材料的组成、结构和性能的影响。在烧结过程中ＴｉＯ２和ＴｉＣ与Ｂ４Ｃ反应原位生成ＴｉＢ２,Ｓｉ和ＴｉＯ２分别与Ｃ反应生成ＳｉＣ和ＴｉＣ,这些陶瓷相的生成对提高炭／陶复合材料的力学性能有显著作用。加入ＴｉＯ２能使炭／陶复合材料在较低的温度下实现致密化烧结,获得了抗弯强度达４３０ＭＰａ的炭／陶复合材料     

Simultaneous Synthesis and Densification of Titanium Oxycarbide, Ti(C,O), through Gas–Solid Combustion

The synthesis of titanium oxycarbide through a solid–gas combustion was investigated. Titanium powders containing TiC additive at levels ranging from 0 to 50 wt% were combusted in an atmosphere of carbon dioxide gas, at pressures ranging from 0.1 to 5.0 MPa. The characteristics of the synthesis process and the properties of the resulting product were found to depend on the level of the TiC additive and on the pressure of the carbon dioxide gas. Dense oxycarbides (∼96% relative density) with Vickers microhardness of ∼18 GPa were synthesized. In addition, the process presents a possible method for the fixation of carbon dioxide gas for the synthesis of useful materials.     

Synthesis of single-phase Ti3SiC2 powder

In this study, free 2Ti/2Si/3TiC powder mixture was heated at high temperatures in vacuum, in order to reveal the possibility for the synthesis of high Ti₃SiC₂ content powder. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the evaluation of phase identities and the morphology of the powder after different treatments. Results showed that almost single phase Ti₃SiC₂ powder (99.3 wt.%) can be synthesized by heat treatment with free 2Ti/2Si/3TiC powders in vacuum at 1210°C for about 3 h. The nucleation and growth of Ti₃SiC₂ within TiC particles was observed. The typical appearance of the formed Ti₃SiC₂ is equiaxed with particle size of 2–4 μm. Effects of temperature and heating time on the morphology and the particle sizes of the synthesized Ti₃SiC₂ powders are not obvious.     

Large-scale fabrication of TiC@C powders and its effect on the properties of Al2O3-MgO-C castables

High performance carbon containing castables have always been pursued by researchers and steelmaking producers, unfortunately, poor water-wettability of graphite flakes was greatly limited their application in castables. To respond this, we proposed a large-scale and low-cost modified molten salt shielding synthesis technique for fabricating TiC coated graphite in air atmosphere using graphite flake and Ti powder as raw materials. Microstructure, wettability and oxidation resistance of TiC@C powders, and effect of TiC@C powders on the properties of Al₂O₃-MgO-C castables were investigated. The results demonstrate that TiC coated graphite was synthesized via modified molten salt shielding synthesis route in air atmosphere. A uniform and continuous TiC layer was formed on the surface of graphite, thereby significantly improving the water-wettability and oxidation resistance of graphite flakes. The castables with 5% TiC@C powders possessed lower apparent porosity, higher cold strength, good oxidation resistance, and slag resistance in comparison with the castables with graphite flakes, and slag resistance were also better than Al₂O₃-MgO castables. The as-fabricated TiC@C powders have good water-wettability and oxidation resistance, making them as a prime carbon source for producing carbon containing castables for steel ladle linings.     

Microstructural Properties of Combustion-Synthesized and Dynamically Consolidated Titanium Boride and Titanium Carbide

Full-density TiB₂ and TiC have been fabricated by combustion synthesis reactions followed by dynamic compaction of the still hot, porous ceramic body. The relationship between the morphologies and purities of the precursor powders used and the ceramic product structures is presented. Intergrain bonding and residual porosity of the dynamically consolidated products are found to depend strongly on the impurity levels of the precursor powders. Analysis of the TiC indicates that density and microhardness increase as a function of the C/Ti ratio, with maximum values at the ratio of 1.0.     

Effect of Al addition on the synthesis of Ti3SiC2 bulk material by pulse discharge sintering process

Ti₃SiC₂ bulk materials were synthesized from the starting powders of 1Ti/1Si/2TiC–xAl and 3Ti/1SiC/1C–xAl (molar ratios, x ranges from 0.05 to 0.15) at temperatures between 1100 and 1400 °C for 15 min by pulse discharge sintering technique. X-ray diffraction and scanning electron microscopy were used to characterize the synthesized materials. It was found that the addition of Al decreases the content of TiC in the sintered samples and expands the optimal temperature range for the synthesis of Ti₃SiC₂ bulk materials. By addition of Al, Ti₃SiC₂ bulk materials of high phase-purity have been synthesized at 1100 and 1200 °C from 1Ti/1Si/2TiC and 3Ti/1SiC/1C starting powders, respectively.     

Structure and mechanical properties of in-situ synthesized α-Ti/TiO2/TiC hybrid composites through mechanical milling and spark plasma sintering

The main aim of this study was to apply high-energy longer mechanical milling and spark plasma sintering (SPS) techniques to produce in-situ α-Ti/TiO₂/TiC hybrid composites from commercially pure-Ti (CP–Ti, HCP structure) powders. The CP-Ti powders were subjected to different milling times (0, 20, 40, 60, 80, 100, and 120 h). The results showed that the powder samples milled for 120 h produced Ti, Ti₃O₅, TiO, TiO₂ phases, and dissolved C atoms from the process control agent (toluene) which were then converted to α-Ti, TiO₂, and TiC phases (formed in-situ composites) through spark plasma sintering. This was expected due to more reactivity in the 120 h sample as longer milling introduces severe and robust structural refinements. Structural evaluations with increasing milling time were carried out using XRD, HRSEM, and HRTEM. The synthesized powders were then consolidated by SPS at pressures of 50 MPa and 1323 K for 6 min. The micro-hardness results have shown that the hardness was started to increase from 1.40 GPa to 5.56 GPa with increasing milling time due to more dislocation and pinning effect produced by grain refinement and formed TiO₂/TiC intermetallic particles enhancing the strength of α-Ti matrix. The α-Ti/TiO₂/TiC in-situ hybrid composite bulk sample yielded an ultimate compressive strength of 1.594 GPa.     

纳米二氧化钛粉的水热合成与光催化性能研究

以钛酸四丁酯(TBOT)为钛源,NH4Cl为分散剂,不经高温煅烧,直接低温水热合成纳米TiO2粉。采用FT-IR,XRD,TEM等方法研究了低温高压水热条件和NH4Cl浓度对TiO2粉的相组成、组织形貌的影响,并研究了其对甲基橙光催化降解的性能。结果表明,纳米TiO2具有锐钛矿相结构且无有机物残留。晶粒尺寸随着水热合成温度增高(120~180℃)而增大,随着NH4Cl/TBOT的摩尔比(0.1~0.5)增加而减小,但纳米粉逐渐出现团聚现象。水热温度为160℃以及NH4Cl/TBOT=0.25条件下合成的锐钛矿相纳米TiO2具有良好的分散性,其颗粒尺寸约为14 nm,且有高的光催化降解甲基橙的能力。