固-固相化学反应法制备纳米铜锰复合氧化物

以碱式碳酸铜、无水碳酸锰与草酸为原料,采用固-固相化学反应法制备了纳米铜锰复合氧化物前驱物,利用正交设计考察了原料中铜与锰的摩尔比、热分解温度及时间对产物纳米铜锰复合氧化物粒径的影响。研究表明,热分解温度对产物的粒径影响最大。最小粒径产物的制备条件是:原料中铜与锰的摩尔比为 1∶2、热分解温度 400℃、热分解时间 2h。XRD和TEM分析结果表明,产物的主要物相组成为Cu0. 425Mn0. 549O2,属立方晶系,Fd3m空间群,平均粒径为 11 .7~19nm。应用TG-DTA和DSC技术研究了纳米铜锰复合氧化物的热分解过程以及热分解动力学,采用Ozawa积分法和Coats-Redfern积分法得前驱物的热分解机理函数均为G(a) =[ -ln(1-α) ]23。

铜/钢双金属固-固相复合法的研究现状及展望

固-固相复合法制备铜/钢双金属复合材料具有生产规模大、投资成本低的优势。目前常见用于铜/钢双金属复合材料的固-固相复合法包括爆炸复合、轧制复合、扩散焊接复合及粉末冶金复合法。通过对比和分析上述几种制备方法的工艺原理及研究现状,提出目前对于固-固相复合法研究的不足,并在此基础上展望了固-固相复合法制备铜/钢双金属复合材料未来的发展方向。

纳米铜锰复合氧化物的固相合成法的研究

目的:探讨纳米Cu1.5Mn1.5O4的室温固相合成法的工艺条件。方法:采用室温固-固合成法制备纳米Cu1.5Mn1.5O4,通过单因素和均匀设计试验,探讨影响产物粒径的因素,确定最佳工艺制备条件;通过X-射线衍射分析(XRD)测得产物粒径,并表征复合氧化物的结构。结果:最小粒径产物的最佳工艺条件:微波加热时间15min,微波功率为540W,热分解时间2.0h,热分解温度370℃,产物主要物相为Cu1.5Mn1.5O4,结构属于立方晶系,空间群为Fd3m。结论:室温固-固合成法制备纳米粉末,具有操作简单、无污染、节能等特点。

五氟化磷制备过程的GC-MS-SIM法评价与监测

比较4种PF5的制备新方法,分别为P2O5和CaF2固-固加热法、KPF6直接加热法、PCl5和CaF2固-固加热法、KPF6和PCl5固-固加热法,并讨论PF5在无水乙醚和乙腈中溶解情况。对4种不同方法反应生成的PF5按照最佳方案经过溶剂预处理,通过GC-MC-SIM法进行评价。研究结果表明:采用P2O5和CaF2固-固加热法生成高纯度的PF5气体,为制备PF5的最优方法,而采用其他3种方法均出现杂质气体产物,分别为PF3和POF3等;对P2O5和CaF2固-固加热法制备PF5过程进行GC-MS-SIM监测,制备过程的最优化方法为:CaF2和P2O5固-固相在质量比≥1:2时,于280℃加热3h。采用该方法时,原材料无毒、易得,制备过程易控制,优于目前传统的PF5制备方法。

不锈钢复合板生产方法和制备技术的探讨

介绍各种不锈钢复合板的生产方法和制备技术 ,着重分析了各种方法的优缺点和技术特点。同时介绍了几种正研究、开发中的新制备技术 ,展望了不锈钢复合方法的发展。

Machine Learning Approach Accelerates Search for Solid State Electrolytes

In the current aera of rapid development in the field of electric vehicles and electrochemical energy storage,solid-state battery technology is attracting much research and attention.Solid-state electrolytes,as the key component of next-generation battery technology,are favored for their high safety,high energy density,and long life.However,finding high-performance solid-state electrolytes is the primary challenge for solid-state battery applications.Focusing on inorganic solid-state electrolytes,this work highlights the need for ideal solid-state electrolytes to have low electronic conductivity,good thermal stability,and structural and phase stability.Traditional experimental and theoretical computational methods suffer from inefficiency,thus machine learning methods become a novel path to intelligently predict material properties by analyzing a large number of inorganic structural properties and characteristics.Through the gradient descent-based XGBoost algorithm,we successfully predicted the energy band structure and stability of the materials,and screened out only 194 ideal solid-state electrolyte structures from more than 6000 structures that satisfy the requirements of low electronic conductivity and stability simultaneously,which greatly accelerated the development of solid-state batteries.

Effects of melt treatment temperature and isothermal holding parameter on water-quenched microstructures of A356 aluminum alloy semisolid slurry

The semisolid slurry of the A356 aluminum alloy was prepared by self-inoculation method(SIM),the effects of melt treatment temperatures and isothermal holding parameters on water-quenched microstructures of A356 aluminum alloy semisolid slurry were investigated,and the solidification behavior of the remaining liquid phase(secondary solidification)was analyzed.The results indicate that the melt treatment temperature has significant effects on the final semisolid microstructures.The semisolid slurry which is suitable for the rheological forming can be produced when the melt treatment temperature is between 680 and 690°C.During the isothermal holding process,the growth rate of the primary particles conforms to the dynamic equation of Dt 3-Do3=Kt,and the coarsening rate of the primary particles is the fastest when the isothermal holding temperature is 600°C.Additionally,the isothermal holding time also has obvious effect on the secondary solidification microstructures.The secondary particles are the smallest and roundest when the isothermal holding time is 3 min.The amount of the secondary particles gradually increases with the increase of isothermal holding temperature,and the eutectic reaction therefore is confined into small intergranular areas,contributing to the compactness of the final solidified eutectic structures.

Solidification process and microstructure of transition layer of Cu-Al composite cast prepared by method of pouring molten aluminum

The Cu?Al composite casts were prepared by the method of pouring molten aluminum. The solidification process and themicrostructure of the transition layer were investigated during the recombination process of the liquid Al and the solid Cu. The results reveal that the microstructure of the transition layer in the Cu?Al composite cast consists of α(Al)+α(Al)?CuAl2 eutectic,α(Al)?CuAl2 eutectic, CuAl2+α(Al)?CuAl2 eutectic and Cu9Al4. Additionally, the pouring temperature, cooling mode of the Cu platesurface and start time of the forced cooling after pouring have no effect on the microstructure species. But the proportion of thevarious microstructures in the transition layer changes with the process parameters. The pure Al at the top of the transition layer startsto solidify first and then the α(Al) phase grows in a dendritic way, while the CuAl2 phase exhibits plane or cellular crystal growth from the two sides of the transition layer towards its interior. The stronger the cooling intensity of the Cu plate outer surface, the more developed the dendrite, and the easier it is for the CuAl2 phase to grow into a plane crystal.

铜/碳钢复合材料的研究现状与展望

碳钢和铜两种金属复合可制成性能优良、具有特殊功能的高品质的复合材料,这种复合材料综合了铁铜两种金属的优点,既有铜优异的导电和耐腐蚀性能,又具有钢的高强度优势。本文介绍了铜/碳钢复合材料的性质、用途制备方法及面临的问题,并在此基础上展望了未来铜/碳钢复合材料的研究方向。铜/碳钢复合材料的耐腐蚀、抗氧化、强度高,导电导热性能优良、广泛应用在通信、电力传输、军工等方面。其制备方法中,电镀法无氰镀铜安全性高,得到的镀层致密平整、光亮均匀,但镀层与基体的结合强度低,会影响界面处结合的稳定性;固-固相爆炸复合法对操作人员的技术要求较为严格,且炸药的选取用量、板间距难以精确把控;利用轧制复合工艺复合的金属材料不具备较高的机械强度,抗扭转性能较弱;粉末烧结法粉体的质量难以保证,且工艺流程复杂,周期较长,生产成本相对较高;固-液相复合法复合的材料界面结合处容易出现夹杂、微孔等缺陷,降低结合强度。

铝基复合材料制备工艺的研究进展

随着目前科技不断的发展,各领域对材料性能的要求越来越高。传统的金属材料已经无法满足社会发展的需要,研究者们把目光集中到了金属基复合材料上。金属基复合材料(MMCs)是可为广泛的工程应用提供量身定制的性能组合的材料,由软金属基体和硬增强粒子组成。对铝基复合材料的制备工艺研究进展进行了简述,分别对固-固法、固-液法、气-液法等方法进行介绍,概括了每种方法的基本原理,分析了它们的优缺点,同时对其今后的发展前景作了展望。

浅谈金的提纯理论与实践

浅谈金的提纯理论与实践张玉明（中原黄金冶炼厂贵金属分厂）低品位固相金（金泥或金与其它金属的合质金等）的提纯途径有两种：一种称固－－固法，即因相金经去除杂质（金属和非金属）得到极高纯度的固相金，另一种称固－－液－－固法，即固相金溶于液相中，经还原得到极...

纳米铜锰复合氧化物前驱物晶粒生长动力学研究

通过对低热固-固化学反应法制备的纳米铜锰复合氧化物前驱物晶粒生长动力学的研究,得到其晶粒生长变化的规律,及晶粒生长激活能和动力学指数的平均值,分别是:E≈33.5kJ/mol,n≈2.80,为其工业化生产提供理论参考依据。

Al、Co、Sc掺杂SiO2微纳材料的制备、结构表征及其对Cr3+和Mn2+的吸附特性

以正硅酸乙酯(TEOS)为硅源,CTAB或SDBS为模板,带结晶水的无机盐(六水氯化铝、六水氯化钴、六水氯化钪)为掺杂物,采用固-固反应法分别制备了Al、Co、Sc单掺杂的SiO2粉体材料。采用XRD、SEM、FTIR等分析手段对所制备粉体材料的结构、形貌等进行了表征;考察了不同表面活性剂、掺杂物、焙烧温度等对SiO2粉体材料吸附性能的影响。结果表明,SiO2微纳粉体材料的形貌为不规则团聚块体,其尺寸处在50 nm^10μm,金属掺杂引起纯SiO2粉体材料XRD衍射峰的微小偏移,红外吸收谱带发生红移,其中以Al-SiO2发生红移程度为最大(1065 cm-1→1081 cm-1);对Cr^3+、Mn^2+的吸附率均比纯SiO2高,并呈现出以下顺序:Al-SiO2>Co-SiO2>Sc-SiO2>SiO2。相同条件下,以CTAB为模板比以SDBS为模板所得的Al-SiO2微纳材料对Cr3+、Mn2+的吸附率大,比纯SiO2粉体的吸附率分别提高了88.5%和90%。

Reconstruction of the Medial Patellofemoral Ligament Using Hamstring Tendon Graft With Different Methods:a Biomechanical Study

Objective To measure the tensile strength of the normal medial patellofemoral ligament(MPFL),and evaluate the biomechanics of different fixation methods of the hamstring tendon graft on the patella.Methods Eight fresh cadaver knees were prepared by isolating the patella,leaving only the MPFL as its attachment to the medial condyle of femur.The MPFL was reconstructed by three different methods:four-suture fixation,anchors-single suture fixation,and anchors-double suture fixation.The tensile strength and the elongation of the normal MPFL and the tendon grafts were measured.Results The tensile strength of the four-suture fixation group(234.86±49.02 N)was stronger than that of the normal MPFL(146.91±25.30 N,P=0.0014)and the anchors-single suture group(159.17±49.07N,P=0.0077),while weaker than that of the anchors-double suture group(314.74±78.46 N,P=0.0052)Conclusions With regard to the tensile strength,the four-suture fixation method is reliable for clinical use.Compared with the anchor-suture method,the four-suture fixation method which has no specific implants is more economical,convenient and efficient.

纳米铜锰复合氧化物的研究进展

纳米铜锰复合氧化物是一种新型高功能精细无机产品,具有独特的结构及表面特性,因而其催化活性和选择性大大高于传统催化剂。综述了纳米铜锰复合氧化物催化剂的特性及制备方法,重点介绍了室温固—固化学反应法,并介绍了国内外纳米铜锰复合氧化物催化剂的应用研究状况,可以作为工业化应用的参考依据。

Effect of bolt inclination angle on shear behavior ofbolted joints under CNL and CNS conditions

Rock bolts are widely used in rock engineering projects to improve the shear capacity of the jointed rock mass.The bolt inclination angle with respect to the shear plane has a remarkable influence on the bolting performance.In this study,a new artificial molding method based on 3D scanning and printing technology was first proposed to prepare bolted joints with an inclined bolt.Then,the effects of the bolt inclination angle and boundary conditions on the shear behavior and failure characteristic of bolted joints were addressed by conducting direct shear tests under both CNL and CNS conditions.Results indicated that rock bolt could significantly improve the shear behavior of rock joints,especially in the post-yield deformation region.With the increase of bolt inclination angle,both the maximum shear stress and the maximum friction coefficient increased first and then decreased,while the maximum normal displacement decreased monotonously.Compared with CNL conditions,the maximum shear stress was larger,whereas the maximum normal displacement and friction coefficient were smaller under the CNS conditions.Furthermore,more asperity damage was observed under the CNS conditions due to the increased normal stress on the shear plane.

Solid−solid phase transition of tungsten induced by high pressure:A molecular dynamics simulation

The phase transition of tungsten(W)under high pressures was investigated with molecular dynamics simulation.The structure was characterized in terms of the pair distribution function and the largest standard cluster analysis(LSCA).It is found that under 40−100 GPa at a cooling rate of 0.1 K/ps a pure W melt first crystallizes into the body-centred cubic(BCC)crystal,and then transfers into the hexagonal close-packed(HCP)crystal through a series of BCC−HCP coexisting states.The dynamic factors may induce intermediate stages during the liquid−solid transition and the criss-cross grain boundaries cause lots of indistinguishable intermediate states,making the first-order BCC−HCP transition appear to be continuous.Furthermore,LSCA is shown to be a parameter-free method that can effectively analyze both ordered and disordered structures.Therefore,LSCA can detect more details about the evolution of the structure in such structure transition processes with rich intermediate structures.

A Method for Determining Available Fixed Ammoniumin Soils

Dynamics of fixed NH in NH-treated soils incubated with glucose at 37±2℃ during the course ofincubation and factors affecting it were studied. Results showed that content of fixed NH in soil reached aminimun on day 7 after incubation and then increased gradually regardless of the amount of glucose addedand the kind of soil tested. However, the amount of fixed NH released from the soil at the given time variedwith both the amount of glucose added and the kind of soil examined. In cases glucose was added at a rateof 10.0g C/kg soil, the amount of fixed NH retained in soil after 7 days of incubation was almost identicalto that found by Neubauer test. Addition of K￣+ depressed the release of fixed NH significantly. Based onthe results obtained a method for determining the content of available fixed NH in soils was proposed andthe amount of N as available fixed NH in two soils measured by this method on an area profile-depth basiswas presented.

A modified preauricular-temporal approach for fixing comminuted and redisplaced zygomatic arch fractures with the resorbable bone plate

Objective： To evaluate the effectiveness of the rigid internal fixation for comminuted and redisplaced zygomatic arch fractures by modified preauriculartemporal approach with the resorbable bone fixation. Methods： Totally twenty patients aged from 14 to 68 years and admitted to our hospital between September 2006 and June 2011 were reviewed, of whom seventeen had a unilateral comminuted zygomatic arch fracture and three re displaced arch fracture after failed closed reduction. The fracture segments were aligned to restore the preinjury form of the arch by rigid fixation with resorbable plates and screws through a modified preauriculartemporal incision. Results： The fractures were well reduced, preauricu lartemporal scar and lateral facial contour were aestheti cally satisfying, and no case had limited mouth opening as well as facial palsy. The resorbable plates were not palpated one year after the operation. Conclusion： The rigid internal fixation through the preauriculartemporal approach with the resorbable bone is an effective method for the comminuted and redisplaced zyomatic arch fractures.

Dynamic solidification mechanism of ternary Ag-Cu-Ge eutectic alloy under ultrasonic condition

The dynamic solidification of ternary Ag38.5Cu33.4Ge28.1 eutectic alloy within a 35 kHz ultrasonic field is investigated and compared with both its equilibrium solidification by DSC method and its rapid solidification in drop tube. The volume fractions of the primary （Ge） phase and pseudobinary （Ag＋ε2） eutectic solidified within ultrasonic field are larger than those formed under equilibrium state, whereas that of ternary （Ag＋ε2＋Ge） eutectic exhibits the reverse trend. During rapid solidification, the liquid alloy droplet directly solidifies into ternary （Ag＋ε2＋Ge） eutectic if its diameter is smaller than 350 um. The ultrasound stimulates the nucleation of alloy melt and prevents the bulk undercooling. With the increase of sound intensity, the primary （Ge） phase transfers from faceted dendrites to nonfaceted blocks with blunt edges, and its grain size is remarkably reduced. Both pseudobinary （Ag＋ε2） and ternary （Ag＋ε2＋Ge） eutectics experience a morphological transition from regular to anomalous structures. This indicates that their cooperative growth mode is replaced by independent growth of eutectic phases under the combined effects of cavitation and acoustic streaming. The ultrasound also shows a prominent coarsening effect to the pseudobinary （Ag＋ε2） and ternary （Ag＋ε2＋Ge） eutectics.