青海低品位磷灰石型磷矿浮选试验研究

对青海某低品位磷灰石型磷矿进行了浮选试验研究。原矿经粗磨后, 可抛除约20%的粗粒黑云母和透辉石。抛尾后试样经再磨后, 采用氧化石蜡皂和2^#药作为捕收剂, 在无碱条件下, 开路试验获得的磷精矿P₂O₅品位为35.41%、P₂O₅作业回收率为87.24%。闭路流程试验获得了磷精矿P₂O₅5 32.01%、P₂O₅作业回收率达97%的良好结果。采用可溶性淀粉可有效抑制磷精矿中的含镁矿物, 从而获取合格的磷精矿。     

高应力复合型软岩巷道支护技术研究

以某矿井底车场巷道为例，通过对围岩物化分析、力学参数、地应力测试，现场工程地质调查及巷道破坏特征分析，针对该矿软岩巷道围岩变形量大和流变变形显著这两个特点，提出了一次支护采用强力锚喷网、二次支护采用锚注支护是适合该矿岩体特点的合理支护形式，并在该矿西大巷延拓及井底车场巷道、硐空修复中成功应用，取得了良好的技术经济效果。     

高应力三软煤层大断面沿空掘巷锚网支护技术

根据采场矿压理论及大型岩土工程分析软件FLAC3D模拟，得出平顶山煤业集团六矿丁5，6—22130风巷沿空掘巷锚网支护合理煤柱宽度并优化了支护参数。矿压监测结果表明，支护设计合理，巷道围岩变形在工程允许范围内，满足了安全生产需要，取得了良好的技术经济效益。     

汽轮机变工况下末两级内的非平衡凝结流动特性研究

汽轮机级内湿蒸汽凝结流产生的水滴会降低汽轮机做功功率,同时对汽轮机叶片带来潜在威胁。为研究不同负荷下汽轮机湿蒸汽内的非平衡凝结流动特性,采用非平衡凝结流动模型对汽轮机末两级叶片进行数值模拟计算。结果表明：不同负荷下,过冷度最大值均在次末级静叶,最大值为20K,然后逐级降低至0K;同一负荷下,汽轮机湿蒸汽级内的湿度大小逐渐增加,且末级动叶20%叶高处的湿度最大,最大值为9.5%;同一负荷下,湿蒸汽的成核率在次末级的静叶处达到最大值,且3种不同负荷下成核率最大值分别是50/（m³·s）、45/（m³·s）、13/（m³·s）;凝结水滴的直径较小,在0～1μm之间。这对汽轮机通流部分设计和改造提供了理论参考。     

页岩弹性模量非均质性对地应力及其损伤的影响

页岩的应力非均质性对钻完井、压裂改造和气藏开发动态等过程具有显著影响,目前未给出合理的表征方法来刻画页岩水力压裂过程中力学非均质性引起的岩石损伤/破裂及应力阴影效应。采用Galerkin有限元数值方法,通过COMSOL Multiphysics求解器,利用Matlab脚本语言进行了二次开发;采用Weibull概率密度函数表示页岩力学非均质性,数值模拟了水力压裂过程中流固耦合条件下非均质性对页岩地应力分布、应变能密度、流压和损伤因子等因素的影响规律。当地层完全为均质时,Von-Mises应力、应变能密度和损伤因子递减分布曲线特征明显,随着地层非均质增强,它们的分布曲线呈现起伏波动的规律,且Von-Mises应力、应变能密度与损伤因子相关性较好。据此提出了二维平面应变条件下力学非均质性引起的岩石损伤/破裂及应力阴影效应表征方法,即用单点线处的Von-Mises应力或应变能密度刻画岩石的局部破裂程度或应力阴影效应的强弱,用单位面积的平均应变能密度刻画岩石整体的破裂程度或应力阴影效应的强弱。该研究对进一步改进页岩体积压裂设计和提高气井产能具有重要指导意义。     

无线电波坑透仪在晋华宫矿8218工作面的实践应用

本文以大同煤矿集团晋华宫矿8218工作面的地质构造为研究对象,采用无线电波坑透技术圈定了8218工作面存在的地质异常区域,通过与其回采实际揭露对比,证实了该工作面所有地质异常区的存在,试验结果表明圈定的位置准确,可以在煤矿其他开采工作面进行推广应用。     

有机共晶中分子带电荷性质的理论研究

本研究选取2种典型的有机共晶体系芘-八氟萘晶体和芘-1,2,4,5-四氰基苯晶体,采用密度泛函理论方法研究其分子带电荷性质,同时系统考察分子堆积对其电荷的影响规律。计算表明有机共晶中分子堆积结构能显著影响分子间的电荷转移,且采用最稳定的两体分子可以近似描述有机共晶中的电荷转移性质。     

渗碳及渗碳喷丸齿轮轮齿弯曲疲劳极限的定量分析

跳出学科分工的局限性,对以齿轮为例的表面强化零件的表象疲劳极限进行综合分析。采用20CrMnTi钢制备三点弯曲小试样及齿轮试样。试样都经过同样的渗碳(并淬火及低温回火)处理,其中一半试样再经过表面喷丸强化。为了对比,还有一组小试样经过伪渗碳处理。测定了小试样表面层的残余压应力场。利用升降法确定了5×106周、应力比0.05条件下小试样和齿轮试样轮齿的弯曲疲劳极限载荷,并对各组试验中疲劳寿命最长的断口进行分析。建立有限元模型,并利用ANSYS软件计算齿轮根部的应力场。利用“疲劳源形成和疲劳极限的微细观过程理论”及“表面和内部疲劳极限”的概念对试验结果进行定量分析,并探讨根据小试样疲劳极限确定复杂零件(如齿轮)疲劳极限载荷的方法,以及表面强化工艺优化的问题。     

等离子喷涂热障陶瓷涂层冷却累计残余应力的有限元模拟与验证

Plasma sprayed ZrO2 ceramic coating has been widely used in many industrial fields due to its simple manufacturing process, low cost, and good heat insulation effect. However, the structure and service conditions of thermal barrier coatings are complex, and residual stresses will inevitably occur during the preparation process as well as application. Residual stress has the most obvious influence on the life of thermal barrier coatings, seriously reducing the bonding strength between the coating and the substrate, and ultimately showing the cracking and spalling of the coating, greatly reducing the service time and stability of the coating during service. To realize the prediction and detection of the residual stress, it is necessary to seek a reliable detection method for thermal barrier coating to effectively predict the accumulated residual stress in the cooling process of coating and reduce the influence of residual stress on the stability of the coating. In this paper, the finite element model of plasma-sprayed ZrO2 coating was established by using the birth and death element method. Gauss heat source was used to simulate the heat source condition of plasma spraying, and the residual stress and its distribution of the coating cooling to room temperature were studied. The residual stress of ZrO2 coating prepared by plasma spraying was detected by X-ray diffraction and Raman spectroscopy to explore the accurate detection method of residual stress in ceramic coating. Through the analysis of the finite element results, it is found that the number of elements is reasonable and the calculation time is short when the mesh unit size of the model is 1.75 mm. The maximum temperature of the coating temperature field obtained by simulation is consistent with the test temperature in the experiment, and the simulation results are accurate. It can be concluded that the residual stresses in the central region of the plasma spraying coating after cooling to room temperature are larger than those in the edge region, which are mainly concentrated in the central region of heat flow. There is large stress at the bonding interface of each layer, which causes the stress to change significantly along the thickness direction of the coating. The equivalent stress of the coating is 160-220 MPa. The X-ray method was used to detect the residual stress of plasma sprayed coating. To obtain an isolated, complete, high peak position and high peak intensity with enough diffraction peaks to avoid the influence of texture, (331) crystal plane with a high multiplicity factor was selected as the characteristic peak. The test results show that the residual stress in the coating will make the position of the characteristic diffraction peak shift to a high angle at 2θ=153°. The residual stresses of 180-185 MPa were detected by X-ray diffraction. The I6 peak in the Raman spectrum of the coating was used as the characteristic peak of the spectrum to represent the frequency shift of the Raman spectrum band. Compared with the original spraying powder, the position of the Raman characteristic peak of the ceramic coating shifted to the low-frequency direction, indicating that there was residual tensile stress after the coating was cooled. The Raman-stress factor of the ZrO2 coating was calibrated to be 8.33 (cm·GPa)-1, and the residual stress of the coating was calculated to be 174-180 MPa. In this paper, the finite element method can effectively simulate the residual stress inside the coating when the plasma spraying reaches room temperature. It has good matching with the XRD and Raman spectrum detection results. There is about 180 MPa residual stress inside the coating when the coating is cooled to room temperature, seriously affecting the stability of the coating. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.