放电等离子烧结(SPS)技术与新材料研究

放电等离子烧结(SPS)作为一种材料的绿色制备新技术,正成为国内外材料领域的研究热点.介绍了SPS的工艺特点和装置、国内外发展状况以及特殊的烧结机理;阐述了SPS在功能梯度材料、生物材料、超细或纳米晶WC-Co硬质材料、镁合金等新材料制备方面的应用及优势.最后分析了SPS技术亟待解决的问题和今后的发展趋势.     

放电等离子烧结技术的原理及应用

放电等离子烧结(SPS)是一种用于材料烧结致密化的新技术，为深入研究和探讨其技术优势，介绍了SPS的基本原理和系统的组成，讨论了SPS技术在纳米材料的制备、梯度功能材料的烧结和高致密度、细晶粒陶瓷制备等方面的应用，并对其研究和应用前景予以展望。     

Mn1.1Fe0.9P0.8Ge0.2室温磁致冷材料的制备新技术

利用机械合金化（mechanical alloying，简称MA）和放电等离子烧结技术（spark plasma sintering，简称SPS技术）制备了Mn1.1Fe0.9P0.8Ge0.2室温磁致冷材料。利用XRD和SEM分析了烧结样品的相结构和显微组织．发现材料在合金化之后形成了单相结构，并在SPS烧结后保持不变。此外DSC的测量结果表明所制备烧结样品的居里温度瓦在-11℃附近，可应用于室温区磁制冷。上述结果说明利用MA和SPS技术合成Mn1.1Fe0.9P0.8Ge0.2是一种简易、有效的新途径。     

放电等离子烧结NdFeB磁体的烧结特征研究

应用放电等离子烧结技术(SPS)制备新型SPS NdFeB磁体.利用扫描电子显微镜(SEM)观察磁体的显微组织,利用B-H回线仪测量磁体磁性能,利用阿基米德法测量样品密度.系统研究了稀土含量不同的两种NdFeB磁体的烧结特征.结果表明,SPS NdFeB磁体的烧结特征与传统烧结方式的特征不同,且与样品稀土含量密切相关;...     

Cu纳米晶块体的制备及纳米晶粒长大动力学研究

采用高能球磨的方法制取金属纳米晶粉末，然后利用放电等离子烧结（SPS）技术制备出金属纳米晶块体材料。设计系列实验研究金属纳米晶材料的晶粒长大行为，获得了纳米晶粒长大的动力学规律。根据已有的工作基础和对实验结果的深入分析，确定动力学参数对稳定相晶粒长大行为的影响。实验发现了高能球磨配合SPS技术制备的Cu纳米晶块体发生快速晶粒长大的临界温度，并结合纳米晶界过剩体积与过剩自由能的关系，分析了纳米晶粒组织的能量因素对晶粒长大行为及动力学的影响。     

放电等离子烧结中颈部形成机理探讨

放电等离子烧结(Spark Plasma Sintering,简称SPS)是一种新的固体压缩烧结技术,它具有升温速度快、烧结时间短、冷却速度快、外加压力和烧结气氛可控、节能环保等鲜明特点,成为材料发展和组织优化的有力工具.SPS在材料制备中的应用越来越广泛,但现阶段对SPS烧结过程的认识远未形成统一观点.SPS过程中颈部的形成是一个关键的阶段,影响到整个烧结过程.本文针对火花等离子烧结颈部的形成机理进行分析认为(1)在SPS烧结非金属材料过程中颈部的形成机理可能是塑性变形和蠕变;(2)导电材料烧结颈部形成过程中可能有火花放电现象发生,其主要机理可能是熔化和凝固、塑性变形、蠕变.同时,本文以纯铜为例,对其SPS烧结过程和结果进行了分析,对烧结过程中颈部的形成情况进行观察,并给出了解释.     

放电等离子烧结(SPS)制备金属材料研究进展

综述了放电等离子烧结(SPS)技术在制备纳米/超细晶、大块非晶、准晶、金属间化合物、功能梯度材料、多孔材料、硬质合金等多种金属材料中的应用情况.重点阐述烧结过程中的致密化机理,焦耳热生成机制,关于等离子活化效应的争议,电流、温度、位移量和应力分布的不均匀性及其影响,粉末的预处理工艺及其对性能的影响.并总结了SPS技术现存问题及发展趋势.     

AgSn18SbTe20无铅中温热电材料的粉末冶金法制备工艺及其对性能的影响

研究了制备p型AgSn₁₈SbTe₂₀无铅热电材料的机械合金化(MA)结合放电等离子烧结(SPS)工艺, 调查了MA过程中球磨时间和SPS温度对材料电热传输性能和热电优值的影响, 分析了样品的物相和显微结构。研究表明, 适当延长球磨时间和降低烧结温度, 可以有效提高材料的热电性能。优化制备条件可以实现59%的性能提升, 最佳条件(球磨12 h、SPS温度743 K)下制备的样品ZT值在723 K达到0.62。     

放电等离子反应液相烧结制备CeB6阴极与性能研究

以氢直流电弧法制备CeH_x纳米粉末, 再采用放电等离子（SPS）反应液相烧结纳米CeH_x和微米B的混合粉末, 制备了高性能CeB₆多晶块体热阴极材料. 研究了SPS制备CeB₆的烧结反应式及反应液相烧结机制, 确定SPS烧结CeB₆的最佳工艺为： 压力50MPa, 烧结温度1500℃, 保温时间5min. 实验结果表明, SPS制备得到了高纯单相CeB6多晶块体, 纯度达到99.89％, 相对密度达到99.61％, 维氏硬度达到2051kg/mm², 抗弯强度达到254.2MPa. 样品在1600℃温度下拐点发射电流密度达到20.38A/cm², 功函数为2.42eV. 与传统制备法相比, SPS制备显著降低了CeB₆的烧结温度, 缩短了烧结时间, 提高了力学和发射性能.     

放电等离子烧结技术与新材料研究

详细介绍了放电等离子烧结(spark plasma sintering，SPS)技术的工艺特点、特殊的烧结机理以及设备发展概况。重点阐述了SPS新材料研究开发的国内外发展状况，包括剃度材料、综合性能优异的稀土永磁Nd-Fe-Co材料、热电能源转换材料(CoSb3系列)、纳米WC-Co硬质材料等。最后展望了SPS新材料在中国的发展前景及应该采取的对策。     

Preparation and characterization of rare-earth bulks with controllable nanostructures

The preparation and characterization of pure rare-earth-metal bulks with controllable nanostructures are reported in this paper. A novel 'oxygen-free' in?situ synthesis technique that combines inert-gas condensation with spark plasma sintering (SPS) technology is proposed. Taking into account the special mechanisms of SPS consolidation and the scale effects of nanoparticles, we introduced practical procedures for preparing rare-earth bulks of amorphous, mixed amorphous and nanocrystals, and nanocrystalline microstructures, respectively. Compared with the conventional polycrystalline bulk, these nanostructured bulks exhibit substantially improved physical and mechanical properties. This technique enables comprehensive studies on the microstructures and properties of a large variety of nanostructured metallic materials that are highly reactive in the air.     

Thermal and mechanical properties of uranium nitride prepared by SPS technique

Nitride fuel is a promising nuclear fuel in fast breeder reactor (FBR) or accelerator-driven subcritical reactor (ADSR) system. In this study, high-density UN pellets were prepared by Spark plasma sintering (SPS) technique. The sample density strongly depended on the sintering temperature and pressure, and the pellets with 90% of theoretical density were easily obtained with low sintering temperature and short sintering time without any milling process. The grain size and pore size were much smaller compared with those for samples prepared by conventional sintering process. Despite of the small grain size, the thermal conductivity remains the high value. The SPS process permits easy densification of nitrides without any deterioration of thermal and mechanical properties, considered to be suitable as a preparation method of nitride fuels.     

制备工艺对n型Bi_2Te_3基材料热电性能和抗压强度的影响

以商用区熔(ZM)n型Bi2Te3基材料为原料,采用简单研磨结合放电等离子烧结技术(ZM+SPS)和熔体旋甩(MS)结合放电等离子烧结技术(MS+SPS)制备了n型Bi2Te3基块体热电材料.对三种不同工艺制备出样品的微结构、热电性能和力学性能进行了研究.FESEM微结构表征结果表明:区熔样品的晶粒粗大,有较强的取向性;经SPS烧结后,晶粒细化,取向性大为降低;而区熔样品经MS+SPS后,晶粒得到进一步细化,且没有明显的取向性.对三组样品进行的热电性能和抗压强度测试,结果表明:区熔原料最大ZT值为0.72(430K),抗压强度仅为40MPa;经SPS后,样品的最大ZT值为0.68(440K),抗压强度为110MPa,相比区熔样品提高了175%;MS+SPS样品的最大ZT值为0.96(320K),其室温ZT值相比区熔样品提高了64%,抗压强度相比区熔样品提高了400%,达到200MPa.     

Spark plasma sintering of sol-gel derived 45S5 Bioglass®-ceramics: Mechanical properties and biocompatibility evaluation

This work aims to find an efficient sintering technique and optimal sintering conditions of a novel sol-gel derived Bioglass®-ceramic powder so as to achieve much improved mechanical properties compared to conventional Bioglass®. To this end, the spark plasma sintering (SPS) technique was for the first time used to densify the sol-gel derived Bioglass®-ceramic powder. It was found that the sol-gel derived Bioglass®-ceramics sintered with the SPS technique at 950 °C for 15 min had a high Young's modulus value of ~ 110 GPa, which was comparable to that of compact bone and significantly higher than the maximal value achieved by the conventional heat treatment. Moreover, the Bioglass®-ceramic compacts sintered with SPS released alkaline ions slowly and as a result, these highly densified Bioglass®-ceramics exhibited better cytocompatibility at the early stage of cell culture testing, compared to the conventional Bioglass®. Hence, the SPS technique is recommended to be used in the process of sol-gel derived Bioglass®-ceramics and its tissue engineering scaffolds.     

Isotropic Mg<Subscript>3</Subscript>Sb<Subscript>2</Subscript> compound prepared by solid-state reaction and ball milling combined with spark plasma sintering

Mg₃Sb₂ compounds were synthesized via low-temperature solid-state reaction (SSR) and ball milling (BM), respectively, followed by spark plasma sintering (SPS) process. The effects of possible sintering pressure-induced orientation in the SPS process have been investigated in terms of the microstructure and thermoelectric transport properties. The results indicate that BM technique causes more severe Mg loss than pure SSR method, leading to distinct Sb phase existing in the product after SPS consolidation process. On the contrary, a single phase of Mg₃Sb₂ is easily obtained with the combination of SSR and SPS techniques. Besides, these BM–SPS and SSR–SPS samples exhibit the similar microstructure as well as the same electrical and thermal transport properties parallel or perpendicular to the direction of sintering pressure. The study suggests that SSR method embodies the advantages of both the composition control and the orientation elimination in Mg₃Sb₂ compound as compared to BM method with the specific parameters in the current work. This investigation is quite favorable for this material fabrication and the future application of thermoelectric modules and devices.     

硅基氧化物发光玻璃及其制备技术研究进展

由于具有高透过率、优异的化学稳定性和易于机械加工等优势, 硅基氧化物玻璃是一种理想的基质材料。通过引入不同的发光组分, 获得不同光学性能的光功能玻璃被广泛应用于多个领域。然而, 这些发光组分在玻璃制备过程中易挥发、分解, 稳定性较低, 所以功能发光玻璃的制备技术仍面临着新的挑战。本文综述了掺杂铋离子、量子点及荧光粉硅基发光玻璃的发展现状及其制备技术。通过比较高温熔融法、溶胶-凝胶法、固相烧结法及放电等离子体烧结技术(简称SPS)的优缺点, 本文着重介绍了SPS技术应用于发光玻璃制备的研究进展及优势, 并对这种新制备技术的发展趋势进行了评述和展望。     

Fabrication of silicon nitride nanoceramics—Powder preparation and sintering: A review

Fine-grained silicon nitride ceramics were investigated mainly for their high-strain-rate plasticity. The preparation and densification of fine silicon nitride powder were reviewed. Commercial sub-micrometer powder was used as raw powder in the “as-received” state and then used after being ground and undergoing classification operation. Chemical vapor deposition and plasma processes were used for fabricating nanopowder because a further reduction in grain size caused by grinding had limitations. More recently, nanopowder has also been obtained by high-energy milling. This process in principle is the same as conventional planetary milling. For densification, primarily hot pressing was performed, although a similar process known as spark plasma sintering (SPS) has also recently been used. One of the advantages of SPS is its high heating rate. The high heating rate is advantageous because it reduces sintering time, achieving densification without grain growth. We prepared silicon nitride nanopowder by high-energy milling and then obtained nanoceramics by densifying the nanopowder by SPS.     

Fabrication of silicon nitride nanoceramics—Powder preparation and sintering: A review

Fine-grained silicon nitride ceramics were investigated mainly for their high-strain-rate plasticity. The preparation and densification of fine silicon nitride powder were reviewed. Commercial sub-micrometer powder was used as raw powder in the “as-received” state and then used after being ground and undergoing classification operation. Chemical vapor deposition and plasma processes were used for fabricating nanopowder because a further reduction in grain size caused by grinding had limitations. More recently, nanopowder has also been obtained by high-energy milling. This process in principle is the same as conventional planetary milling. For densification, primarily hot pressing was performed, although a similar process known as spark plasma sintering (SPS) has also recently been used. One of the advantages of SPS is its high heating rate. The high heating rate is advantageous because it reduces sintering time, achieving densification without grain growth. We prepared silicon nitride nanopowder by high-energy milling and then obtained nanoceramics by densifying the nanopowder by SPS.     

相互缠结的聚甲基丙烯酸甲酯/磺化聚苯乙烯复合水基微乳液的研究Ⅰ.复合水基微乳液的制备及影响因素

将聚苯乙烯制成磺化聚苯乙烯离聚体（SPS），利用相反转技术，将磺化聚苯乙烯离聚体加水制成具有纳米级的稳定的水基微乳液，利用SPS纳米微粒核内部作为反应场所，用引发剂引发亲油性单体甲基丙烯酸甲酯聚合，制备具有相互缠结结构的PMMA／SPS复合水基微乳液，研究了引发剂的用量，MMA的用量，溶剂极性对聚合反应及复合水基微乳液的影响。