摘要:A dynamic model of two-degree-of-freedom vibro-impact system with dry friction excitation is established. The gliding, stick sliding, scratch cutting and collision are analyzed, and the equation of motion and the engagement conditions are worked out. The complex dynamics behavior is solved and analyzed by employing the value iteration method. And the influence of dry friction and the drive oscillation amplitude on the systems dynamics is studied.%建立干摩擦下舍间隙的双自由度碰撞振动系统的动力学模型,分析系统中存在的滑动、黏滑、擦切及碰撞等运动,分别给出其运动方程和衔接条件,并采用数值迭代方法求解和分析系统的复杂动力学行为,同时分析了干摩擦和激励振幅对系统动力学行为的影响.
摘要:An empirical formula of blasting vibration velocity attenuation is proposed in this paper by field test in the Yangtze River Taiziji Waterway dredging blasting project. The safety criteria of the blasting velocity and the max allowed explosive under different conditions are presented. The effect of the underwater drilling blasting is assessed based on the measured data so as to ensure the safety of the Yangtze River levee.%以长江太子矶航道疏浚爆破工程为例,通过对其爆破地震波的测试与分析,得出爆破振动速度的衰减经验公式,提出爆破振动速度安全判据及不同状态下的最大允许药量,并依据实测数据评估了水下钻孔爆破对长江大堤的影响.
摘要:The key to analyzing slope stability using FEM strength reduction method is to determine whether the slope reaches its limitation. Presently, there are mainly three criteria of unstable slopes: the non convergence of FEM calculation, the abruptness of slope displacement and the connectivity of plastic zone on potential slip surface. Based on the analysis of the advantages and disadvantages of the three methods, a comprehensive criterion is suggested for slope stability:the small deformation FEM with the criterion of non convergent calculation is calculated first, followed by a large one with the cri-terion of displacement abruptness. The stability of an ACADS example slope and a foundation slope are analyzed with ABAQUS. The analysis is compared with the results obtained by adopting the Bish-op method. It is found that the discrepancy of safety factor between the two results is close, which proves the feasibility of the proposed criterion.%在分析有限元计算不收敛、坡体位移突变和潜在滑移面塑性区贯通这3种边坡失稳判据优缺点的基础上,提出边坡失稳的综合判据法,即先进行小变形有限元计算,以计算不收敛为边坡失稳判据,后进行大变形有限元计算,以位移突变为判据.采用综合判据法、运用ABAQUS有限元软件对一个标准算例和一个工程实例进行边坡稳定性分析,并与常用的简化Bishop法进行比较,二者所得安全系数接近,证明了边坡失稳综合判据法的合理可行.
摘要:This paper studies the average distance from the points within the plane convex domain to the boundary points. Through the deformation of kinematic formulas and the translation of the aver-age distance into an integral of power chord, the average distance of the corresponding parallelogram is obtained.%针对平面凸域的内点与边界点的平均距离问题,通过对运动公式的特别变形,将平均距离转化为弦幂积分,进而得到平行四边形的平均弦长以及平行四边形内点与边界点的平均距离计算公式.
摘要:To provide an important parameter for the hydraulic cylinder design, a set of hydraulic cylin-der experimental data were obtained and analyzed. Normal membership function of hydraulic cylin-der's critical pressure was constructed based on the statistics result and the static stability was worked out. The experiment shows that the method is effective.%为了给液压缸稳定性设计提供一个参照指标,对液压缸的一组实验数据进行了分析处理,构造了液压缸临界压力的正态型隶属度函数,从而计算出液压缸静力稳定性可靠度,计算实例表明该方法有效.
摘要:Based on coupling a continuum damage factor,a damage rheological model of asphalt mixture that can describe total creep behavior is presented in this paper. A constitutive equation of the model is established with the viscoelastic characteristics and damage taken into account. Through uniaxial creep experiments under different stress amplitudes, nonlinear fitting program is worked out, the model parameters calibrated, and the curves of damage evolution obtained. The comparison between the model and experiment data shows that the damage rheological model successfully presents the characteristics of the creeping process and the damage critical time under various loading stress ampli-tudes. And the traditional Burgers model prediction is presented for reference.%在三元件黏弹性模型基础上耦合一个连续性损伤因子,构建一个能够描述沥青混合料三阶段蠕变全过程的损伤蠕变模型.综合考虑黏弹性特性与损伤机制,推导了该模型的本构方程,分析了沥青混合料的蠕变特性.通过沥青混合料在不同应力水平下的单轴压缩蠕变实验,编制非线性拟舍程序,得到模型参数和损伤演化曲线.将不同应力条件下模型预测值与实验结果进行对比,结果表明,该模型能准确反映不同应力水平下沥青混合料蠕变过程三个阶段的特征和进入破坏阶段的临界时间.
摘要:A resource discovery model based on the layer structure was set up. The overlay network constructed in cycle shift has guaranteed the quality of service of resource discovery. In order to dis-seminate the resource information to the whole network in a limited jumping number and reduce re-dundant information, the algorithm of message expanding M flooding was designed. The model is found to have good efficiency and reliability.%提出一种基于层次结构的混合式网格资源发现模型.模型中采用循环移数结构来构建覆盖网络,保证了资源发现的服务质量.为了使资源信息能在有限跳数内扩散到整个网络,同时减少消息冗余,设计了M-flooding消息扩散算法,确保模型具有较好的资源发现效率和较高的可靠性.
摘要:针对A356铝舍金轮毂多道次旋压成形,运用Abaqus软件建立了轮毂多道次旋压有限元模型.通过对汽车轮毂多道次旋压成形过程进行数值模拟,得到其坯料的应力应变分布云图,并分析了轮毂各道次下减薄率、进给比、旋轮圆角半径等工艺参数对旋压力的影响.从分析中发现轮毂各道次下减薄率是影响旋压工艺的主要因素.%The finite element model of A356 hub multi-step spinning was established on the basis of the FEA software Abaqus. By numerically simulating the spinning process, the distributions of effective stress and strain of the blank were obtained. The effects of the main process factors on the spinning force, including percent reduction, roller nose radius and feed ratio, were analyzed. Through the a-nalysis, the feed ratio of each step is found to have the primary effect on the spinning process.
摘要:In order to improve the indices of pellets of Chengchao Iron Mine, laboratorial pelletization tests were carried out with bentonite, organic binder and composite binder as pelletizing binders. The results show that, all the three pelletizing binders have a certain impact on the quality of pellet prod-uct; however, the former 2 binders will lead to high cracking temperature and lower strength of green balls which will not meet the industrial requests. The composite binder which, however, makes the best use of bentonite and organic binder, greatly improves the indices of green balls with the preheated pellet strength at 14. 5 N, wet knock strength at 12. 1 per 0. 5 m, burst temperature at 630℃, and fired pellet strength at 3 024 N, which satisfies the requests of production.%对程潮铁矿高压辊磨前后的铁精矿分别添加膨润土、有机黏结剂、复合黏结剂进行造球试验.结果表明,单独添加少量的膨润土或有机黏结剂,其生球爆裂温度指标合格,生球强度指标不合格;采用膨润土质量分数为2.0%、有机黏结剂质量分数为0.05%的复合黏结剂,其生球抗压强度为14.5 N/个、生球落下强度为(0.5 m)12.1次/个、生球爆裂温度为630℃、成品球抗压强度为3 024 N/个,球团质量有较大的提高.
摘要:讨论一维p-Laplace方程在Dirichlet边值条件下的非线性特征值问题,并结合Leray-Schauder度理论以及标准分支定理,讨论一维p-Laplace方程边值问题解的整体分支结构.%This paper discusses the nonlinear eigenvalue for the p Laplace equation with the Dirichlet boundary condition in one dimension. And Leray Schauder degree theory and the standard global bi-furcation theory are used to get the global bifurcation structure for the p Laplace equation in one di-mension.
摘要:Continuous batch processing is a new batch processing method with which the processing time depends on the batch size, the max processing time of the batch, and the capacity of the batching machine. In this paper we consider minimizing the total weighted completion time. We analyze the properties of optimal solution, and provide the method for sequencing the jobs in a batch and sequen-cing the batches. With regard to the disagreeable weight and processing time, a dynamic program-ming algorithm is presented.%连续型批处理机调度问题是从钢铁生产线提炼出来的一种新型的批调度模型,该调度模型中,批的加工时间取决于该批的大小、批中工件的最大加工时间及机器的容量.研究目标函数为最小加权总完工时间的单机连续型批调度问题,分析最优解的性质,讨论最优的批内、批间序及分批策略,给出工件权值与加工时间逆序情况下的动态规划算法.
摘要:对PEF250×400复摆颚式破碎机动颚的运动轨迹进行分析,以特征点的行程比和偏心轴距为综合优化目标,选取8个设计变量并确定5个方面的约束条件,对动颚运动轨迹进行优化.结果表明,在基本保持破碎机产量的条件下,给、排料口处的行程比明显降低,偏心轴距也得到减小.%In this paper, the moving jaw track of PEF250×400 compound swinging type jaw crusher is analyzed and optimized. The optimization objectives are the displacement ratio of characteristic points and shaft eccentricity. Eight design variables are selected and five major constraints are identified for the optimization purpose. The results show that the displacement ratio is markedly improved while the output is maintained and the abrasion of the jaw liner plate is effectively reduced.
摘要:研究平面凸体的弦长分布问题,运用积分几何的理论与方法,通过推广支持函数,求得了矩形域弦长的分布函数.%This paper studies the chord length distribution of a plane convex body. By promoting sup-port functions and making use of integral geometry theory and methods, the chord distribution func-tion of rectangular is obtained.
摘要:运用非线性有限元软件ABAQUS对ITER计划导体套管成形工艺进行模拟仿真,得到稳定拉拔阶段的等效塑性应变、轴向和径向应力以及接触压力的分布规律,并分析了拉拔力和拉拔成形过程中能量的分布变化.结果表明,采用优化后的工艺参数拉拔成形时可得到套管内外表面质量较好的产品,从而解决了拉拔工艺中材料内径缩孔和裂纹缺陷的问题.%Conductor tubes with ITER PLANS, as a special square circular tube, are easy to have shrinkage, cracks and other defects during the drawing process. In this study, the deformation of conductor tubes was simulated and calculated by using a nonlinear finite element software ABAQUS, and the equivalent plastic strain, axial stress and radial stress of the stable drawing were obtained. Contact pressure distribution and the law of drawing force and energy distribution during drawing deformation were also analyzed. The experiment shows that better quality of the inner and outer surfaces of the tube is achieved after optimizing the process, which provides a reference for approaching such defects as cracks and shrinkage of the inner tube.
摘要:Texture evolution during tensile deformation and the weakening of <111> texture by twinning at room temperature were investigated in coarse-grained high manganese TWIP steels with 26% and 30% manganese, respectively. The results show that a dominant (111) texture develops during tensile deformation, and at the same time weak textures close to the <100> orientation are formed due 'to the twinning of <111) matrix grains, which weakens <111) texture. Coarse austenite grains facilitate twinning and thus accelerate < 111 > texture weakening. Besides, during tensile deformation austenite grains of < 111 > orientation are easy to twin, while grains of <100> orientation are difficult to twin. Small amount of e-martensite is induced during tension in 26Mn steel of lower manganese content and it forms mainly within the twins in -oriented matrix. Therefore, it weakens < 111 > texture of matrix on the one hand and is also preferentially oriented producing a tilt basal microtexture on the other hand.%研究室温下锰的质量分数分别为26%和30%的两种晶粒较粗大的TWIP钢拉断过程中织构的演变规律及孪生弱化〈111〉织构的作用.结果表明,TWIP钢拉伸时形成较强的〈111〉织构,也形成由〈111〉取向晶粒的不同孪晶产生的接近〈100〉的弱织构,从而孪生弱化了〈111〉拉伸织构.粗的奥氏体晶粒促进孪生,从而加速〈111〉织构的弱化.拉伸过程中〈111〉取向的晶粒有利于形变孪生,〈100〉取向的晶粒不利于孪生.锰含量较低的26Mn钢出现少量的形变诱发ε-M,由于ε-M主要从〈111〉取向的形变孪晶内形成,因此也出现择优取向,形成倾转的基面织构,弱化了〈111〉织构.
摘要:The SEM sample of isotactic polypropylene (iPP) was prepared by means of kalii permanganate etching, and the spherulites morphology of the sample was observed with the SEM. It is found that the sample that has been steeped in the kalii permanganate solution for about 1 hour demonstrates clear spherulites morphology, and oriPP spherulites have mother and daughter molecular structure. The amorphous parts between the mother molecules are etched into radiating stripes, and the amorphous parts between the mother and daughter molecules have grid pits on the surface after the etching.%用高锰酸钾溶液蚀刻方法制备全同聚丙烯(iPP)的SEM分析试样,观察iPP试样的球晶形貌,结果表明,经高锰酸钾溶液浸泡1h左右的iPP试样,SEM观察下可以获得细节清晰的球晶形貌,α-iPP球晶具有子母晶片结构,母晶片间的非晶组织被蚀刻后呈放射状腐蚀条纹,子、母晶片间的非晶部分被高锰酸钾溶液蚀刻后留下格子状的腐蚀坑.
摘要:将两种软化剂分别掺入煤沥青,制得软化煤沥青,再与石油沥青混合,经SBS改性后得到复合改性炭沥青.采用四组分分析法和胶体不稳定指数(Ic)研究复合改性炭沥青的胶体稳定性.结果表明,加入适量的软化煤沥青能够增加复合改性炭沥青中沥青质含量,减少饱和分含量,同时达到调节芳香分和胶质含量的作用,使复合改性炭沥青的四组分含量分布合理.所制复合改性炭沥青的Ic值较低,胶体体系稳定.%Two kinds of softener were mixed in coal tar pitch to obtain softened coal tar pitch, which was then mixed with petroleum asphalt. The new mixture was modified by SBS to get the modified anthraxolite compound. The colloids stability of the anthraxolite compound was studied by employing quartering analytical method and colloid instable index (Ic). The results show that the content of as-phaltene was increased and that of saturates was reduced by appropriate amount of softening coal tar pitch, while aromatics and colloid were regulated. Four components of the modified anthraxolite were distributed to a reasonable extent. The value Ic of modified anthraxolite compound was low and the colloidal system was steady, which was beneficial to improving its ageing resistance and storage stability.
摘要:On the basis of the model of 1D compressible flow in the straight constant section adiabatic duct with wall friction, the expression of the flow rate parameter function S/A (the ratio of the effective duct section area to the cross-section area) and b (the critical pressure) of the pneumatic duct was deduced with the velocity in the duct import section as the independent variable. With a new algorithm that calculates the average friction factor of the adiabatic pneumatic duct from on-site friction factor, the flow rate parameters S and b of the pneumatic duct of 1 - 50 m in length and 2. 5~9 mm in diameter under an inlet stagnation pressure of 0. 6 Mpa and a stagnation temperature of 300 K were calculated directly and compared with the empirical values. It is found that the variable tendency of the calculated curve equates that of the empirical curve, and the calculated values correspond to the empirical values, which implies that the new algorithm can reflect the physical essence of the variation of the flow rate parameters to a certain extent. By reducing the calculated value of S by 20% and increasing the calculated value of b by 40%, the values obtained can be employed for the selection of the pneumatic nylon duct under similar conditions.%在等截面直管绝热有壁面摩擦一雏可压缩管道流动模型的基础上,推导以管道进口截面速度因数为自变量的气动管道流量特性参数函数S/A(管道有效截面积与横截面积之比)和临界压力比b的基本表达式.采用基于当地摩擦因数求解管道平均摩擦因数的新方法,直接计算出总压为0.6 MPa、总温为300 K、长度为1~50m、内径为2.5~9 mm尼龙管的流量特性参数S和b,并与经验值进行了比较.S和b的理论计算值与经验曲线变化趋势相同,且计算值与经验值相吻合,表明新方法可以在相当程度上反映气动管道流量特性参数变化的物理本质.将新方法得到的有效截面积S的理论计算值下跌20%、临界压力比b的理论计算值上浮40%,即可作为同等条件下选用气动系统尼龙管的经验推荐值使用.
摘要:应用以可靠性为中心的维修(RCM)方法对冶金单体设备的维修策略进行研究.以开卷机为具体对象,引入役龄回退因子对设备役龄进行修正,采用威布尔分布对设备的故障间隔时间进行拟合,得到设备的故障率函数,并以设备维修总成本最小化为目标,建立基于可靠性和经济性约束的不完全预防性维修模型.通过一个算例对该模型进行了验证.%Metallurgical equipment maintenance strategy was researched by adopting the reliability centered maintenance (RCM) method. Age reduction factors were introduced to revise the service age of the decoiler. Weibull distribution was used to fit the failure interval of the equipment with the failure function obtained. To minimize the maintenance cost, a preventive maintenance model for the single metallurgical equipment was established. And the model was validated with an example.
摘要:Evolution of the textures of hot rolled, cold rolled and annealed IF steel samples is studied in this paper. The advanced electron backscatter diffraction (EBSD) technique and XRD are employed to calculate and determine the orientation distribution functions and texture components of the samples. The results show that dynamic recrystallization takes place during hot rolling and that the grains of the hot rolled sample are small and equiaxial, which forms the basic microstructure for the next process. The texture of the hot rolled sample is found to be weak which will not affect the texture components and their percentages in the descendent cold rolling. The texture components are formed mainly during the cold rolling process. There are mainly four texture components in the cold rolled sample, and the order is {001} <110>, {111} <110>, {111} < 112> , {112} < 110>. All the four components transfer to the {111} plane texture during the recrystallization annealing.%对IF钢生产过程中热轧、冷轧及退火试样的织构演变进行研究.分别借助EBSD和XRD测定和计算了热轧、退火及冷轧试样的取向分布函数及相关织构组分的体积分数.结果发现,热轧板在变形过程中发生了动态再结晶,晶粒为细小的等轴晶,为后续组织发展提供了基础;热轧后试样中的织构很弱,不会影响冷轧织构组分及含量.冷轧过程是织构形成的主要过程,试样中含有4种主要的织构组分:{001}〈110〉、{111}〈110〉、{111}〈112〉和{112}〈110〉.退火过程中发生再结晶,4种冷轧织构组分在退火过程中均分别转变为{111}面织构.
摘要:The effect of preparation processes of the vanadium-titanium catalyst such as vanadium content, calcination time, additive and number of impregnation times on the catalyst's surface structure and property for catalytic combustion of o-dichlorobenzene were investigated. The catalyst was characterized by means of diffuse reflectance UV spectroscopy (DRUVS), X-ray diffraction spectrum (XRD) and the BET technique. The results show that the active sites on the surface of the catalyst increase with the increase in V loading and the catalytic performance is enhanced. Prolonging calcination time results in the aggregation of vanadium species and a decrease in the specific surface area, yet is beneficial to producing oligomeric active vanadium and hence improving the catalytic performance. Both tungstic oxide additive and multiple impregnation method are beneficial to generating well dispersed active vanadium and inhibiting the aggregation and polymerization of surface vanadium. Further results of DRUV indicate that monomer and oligomeric vanadate are the active sites of the VOX/ TiO2 catalyst and polymeric vanadium has a negative effect on the catalytic decomposition of o-dichlorobenzene.%研究V2 O5/TiO2催化剂的制备工艺,如载钒量、煅烧时间、助催化剂和浸渍次数等,对催化剂表面结构及催化分解气相邻二氯苯的影响.采用漫反射紫外光谱(DRUVS)、X射线衍射(XRD)、BET等方法对催化剂进行表征.结果表明,随着载钒量的增大,催化剂表面活性物质含量增多,催化性能增强;延长煅烧时间会导致催化剂的团聚增加、比表面积减少,但有利于催化剂表面生成低聚态活性钒和V4+,从而提高其催化活性;添加助催化剂WO3和采用多次浸渍均能抑制活性钒的团聚,促进表面低聚态活性钒的分散;单聚和低聚钒酸盐是VOx/TiO2催化剂的活性物质,而高聚钒对催化分解气相邻二氯苯有抑制作用.
摘要:Factsage? Was employed to calculate the phase diagram of four kinds of slag systems for high phosphorus hot metal dephosphorization pretreatment at the temperature of 1 623 K, with B2O3, K2O, MnO2 and TiO2 in replacement of CaF2 for fluxing. It was found that there appeared liquid slags in most regions in the phase diagrams. Based on the computed phase diagrams, slag scenarios of dephosphorization experiments were determined. And the slagging in the tests basically agreed with the information presented by the computed phase diagrams.%采用FactsageTM软件对以B2O3、K2O、MnO2、TiO2代替CaF2助熔的4种高磷铁水预处理脱磷渣系在1 623 K时的相图进行计算,发现相图中的多数区域都有液态渣出现.根据计算相图制定脱磷实验的配渣方案,实验过程中观察到的化渣情况与计算相图提供的信息基本一致.
摘要:对540 MPa级铁素体/贝氏体双相钢的组织性能进行分析研究.结果表明,试验钢的显微组织为85%左右的铁素体加上15%左右的贝氏体;铁素体晶粒尺寸细小,基体中有较高的位错密度和大量细小弥散的析出物;贝氏体在铁素体基体上分布均匀,以板条状为主,板条间分布有较多碳化物颗粒.通过合适的成分设计和控轧控冷手段获得的铁素体/贝氏体双相钢组织形态,可较好地保证材料所需的强度-拉伸凸缘性能匹配.%The mechanical properties and microstructure of 540 Mpa grade ferrite/bainite dual-phase steel were investigated. The results show that the tested steel is made up of about 85% ferrite and 15% bainite. The fine grain ferrite has high dislocation density and massive fine precipitates. The bainite is mainly lathy with many carbide articles and distributes among ferrite equably. This dual-phase microstructure obtained by appropriate chemical composition design and TMCP guarantees the required strength and stretch-flangeability of the material.
摘要:以国产双喷嘴挡板电液伺服阀为研究对象,推导出其数学模型.根据电液伺服阀的实际结构参数,运用Simulink仿真软件对数学模型进行仿真,得到电液伺服阀闭环阶跃的响应图和伯德图.通过改变目标参数Kvf、ωmf、ξmf的大小,得到不同的电液伺服阀伯德图;通过分析电液伺服阀动态性能的变化,从而达到其参数优化的目的.%In this paper, a certain home-made dual nozzle flapper electro hydraulic servo valve is studied and its mathematic model is deduced. According to the actual structure parameters, with Simulink software simulation, the closed loop order servo valves step response figures and Bode figures are obtained from the simulation. By changing the main target parameter Kvf, wmf, ζmf, different Bode figures are obtained. To achieve the parameter optimization of the servo valve, the alteration of the servo valve dynamic performance is analyzed.
摘要:Based on the investigation of various battery models available, a simplified model based on mass transfer for characterizing the performance of Li-ion battery IHR18650 in COMSOL v3. 5 was proposed and validated through several predefined discharging experiments. The model-based simulation shows that the model can accurately describe the external features of the Li-ion battery. Based on this model, simulation analysis is carried out to study the distribution of Li-ion concentration, the potential under different charging/discharging current, the effect of design parameters on battery performance, and the variation of Li-ion concentration and potential distribution along with the change in charging/discharging current.%在比较分析各类蓄电池系统模型的基础上,提出一种基于传质现象的锂电池简化机理模型.采用COMSOL v3.5软件针对型号为IHR 18650的锰酸锂离子电池进行仿真研究,并通过放电实验对简化模型的有效性进行验证.结果表明,提出的简化模型能够较为准确地描述锂离子电池的外部特性.文中进一步对不同充/放电电流条件下的锂离子浓度和电势分布情况、设计参数对锂电池性能的影响以及锂离子浓度和电势分布随电池充/放过程的变化情况进行了仿真分析.
摘要:采用不同的时效工艺,运用冲击试验、俄歇能谱、扫描电镜等分析方法,研究2.25CrlMo钢的韧脆转变温度变化规律及其影响因素.结果表明,2.25CrlMo试验钢650℃时效2h后的韧脆转变温度为-55℃,560℃时效100 h后的韧脆转变温度为-25℃,480℃时效1 200 h后的韧脆转变温度升高至-10℃;P在晶界处的偏聚行为是导致试验钢韧脆转变温度变化的主要因素.%The ductile-to-brittle transition temperature (DBTT) was investigated by means of impact test, AES and SEM, etc. The results show that the DBTT of the samples aged at 650 ℃ for 2 hours is -55 ℃ and that at 560 ℃ for 100 hours is -25 ℃. After aging at 480 ℃ for 1 200 hours, the DBTT of the samples rise to -10 °C. And the grain boundary segregation of phosphorus is the leading factor that influences the variation of the DBTT of the tested steel.
摘要:以天然镁橄榄石和NaCl为原料,采用熔盐法制备镁橄榄石质隔热材料.研究不同熔盐配比和烧结温度对材料显气孔率、体积密度和耐压强度的影响,并利用X射线衍射仪(XRD)和扫描电镜(SEM)对其相组成及微观形貌进行表征.结果表明,熔融的NaCl提供了液相环境,促进了镁橄榄石的烧结,经过水溶液处理后,NaCl溶于水中,其占据的空间形成了气孔;烧结温度为1 100℃,熔盐含量为50%时,制得的隔热材料有较低的体积密度、较高的显气孔率和耐压强度,气孔分布更均匀,材料的隔热性能较佳.%Forsterite thermal insulation materials were prepared by the molten salt method, with natural forsterite and NaCl molten salt as raw materials. The influences of different mass ratios and reaction temperatures on thermal insulation materials were investigated. Apparent porosity, bulk density and compressive strength of the samples were characterized, and phase composition and microstruc-ture were analyzed by X ray diffraction and scanning electron microscopy. The results demonstrate that, when the sample is sintered at 1 100 °C and the content of molten salt is 50 wt%, the forsterite thermal insulation materials have lower bulk density, higher apparent porosity and higher compressive strength, with uniform distribution of pore size and better heat insulation performance. The reason is that molten NaCl has provided liquid environment and promoted the sintering of forsterite, and pores are formed after the removal of NaCl.
摘要:By changing the flow structure of the clearance of the aerostatic thrust bearing, this paper deduces the control equation for the 2D diffusion irrotational supersonic symmetry flow in the circular aerostatic thrust bearing of variable film thickness, based on which the characteristic line equation and ' compatibility equation are further derived. The analytic solution of ID supersonic flow in the gas film of equal clearance is used to verify the characteristic line equation and compatibility equation. The results show that, when interior point spacing is appropriate, the results of the characteristic numerical method is very close to those of the analytical solution, and the characteristic line equation and compatibility equation are correct.%通过改变止推气体轴承等间隙的流道结构,对变气膜厚度圆盘止推气体轴承中二维无旋超音速扩散对称流动控制方程进行推导,得出其特征线方程和相容性方程,对所得特征线方程和相容性方程用等间隙气膜内一维超音速流动的解析解进行验算.结果表明,当内点间距合适时,特征线法数值求解与解析解结果十分接近,推导的特征线方程和相容性方程正确.
摘要:采用小型间歇消化装置,用正交试验法研究消化参数对石灰干式消化速度及消石灰结构性能的影响.实验结果表明,消化参数对消化结果的影响从大到小排序为:消化时间>水灰比>搅拌速度>消化水初始温度.优化后的工艺参数:消化时间为5~10 min;水灰比(摩尔比)为1.3~1.6;搅拌速度为250~300 r/min;消化水初始温度为25~45℃.优化工艺参数下制备的消石灰比表面和孔隙率最大可达25.69m2·g-1和75.09%.%A set of small batch slaking system was used in experiments for investigating the effects of technological parameters on the dry slaking speed of quicklime and the properties of slaked lime by means of orthogonal experimental method. It is found that the factors impacting the slaking process from high to low are slaking time, water/solid ratio, stirring rate, and initial temperature of slaking water. On this basis, the optimal conditions of the dry quicklime slaking process are proposed to be 5 ~10 min in slaking time, (1. 3~1. 6) ! 1 in water/ solid ratio, 250 '-300 r/min in stirring rate, and 25 ~45 °C in initial temperature of slaking water. Correspondingly, the largest specific surface and porosity of the last dry white lime are 25. 69 m2 ? G-1 and 75. 09% respectively.