Enhanced piezoelectricity and non-contact optical temperature sensing performance in Er3+ ion modified (K,Na)NbO3-based multifunctional ceramics

Rare earth ions doped ferroelectrics have attracted wide attentions due to their multifunction characteristics with both ferroelectric/piezoelectric properties and intriguing photoluminescence performance, which show great prospects for future multifunctional devices. In this work, a novel rare earth Er³⁺ ion modified potassium-sodium niobate (KNN) based ceramics were elaborately designed and prepared by the conventional solid-state reaction. The microstructure, phase structure, electric properties and photoluminescence performance of the Er³⁺ ion modified KNN-based ceramics were systematically investigated. Enhanced piezoelectricity (a considerable d₃₃ of exceeding 300 pC/N and a large d₃₃* up to 500 p.m./V) was realized through optimizing the substitution of BaZrO₃ by (Er_0.5,Na_0.5)ZrO₃. Both down-conversion and up-conversion photoluminescence emissions were detected in the optimal composition. The temperature-dependent upconversion emissions of the optimal Er³⁺ modified ceramic sample in the temperature range of 303–573K were verified to be applicable for non-contact optical temperature sensing with a maximum sensitivity S_a of 0.0028 K^-1 and a peak relative sensitivity S_r of 0.96% K⁻¹. Moreover, low-temperature sensing performance with a maximum S_r of 16.7% K⁻¹ in the temperature range of 80–280K was also presented based on the temperature-dependent down-conversion emissions. With both decent electrical properties and intriguing photoluminescence performance, the Er³⁺-modified KNN-based ferroelectrics exhibit good application potential in the future multifunctional optoelectronic devices.     

复杂采空区下残留磷矿层的回收

为有效回收荆门市某磷矿Ph1下矿层底部残留的泥质条带状青矿层,针对矿层较薄、产状较缓、赋存不稳定、上覆空区分布复杂、回采难度大、矿石附加值低等特点,探索采用小矿房、密矿柱、底盘机械出矿、盘区框架矿柱隔离的方式开采,实际采矿回收率达50%以上,项目完成将可回收271.8万t的遗弃磷矿资源。实践表明,该采矿方法达到了低耗、安全、高效回收遗留残矿的目的,经济效益显著。     

矿用不间断电源锁相控制技术的研究

为了满足矿用不间断电源锁相的稳定和高精度的要求,提出了一种基于TMS320F2812的软件锁相控制技术。这种算法锁相精度高,稳定性好,抗干扰能力强,并通过实验验证了所用算法有效可行。     

Preparation of high-quality FeV50 alloy by an improved SHS-EAH multi-stage process

As the most widely used vanadium intermediate alloy, ferrovanadium is mainly prepared by the self-propagating high-temperature synthesis (SHS) process with the advantages of short process and large heat release. However, there is a trade-off between the amount of reduction agent of Al and the product quality of ferrovanadium, which is caused by the thermodynamic equilibrium limitation of the reduction between Al and vanadium oxides. The reasonable adjustment of the trade-off has become an urgent problem to be solved for the preparation of high-quality ferrovanadium. In the present work, the thermodynamic equilibrium for the reduction limitation using Al as reducing agent has been thoroughly analyzed with the reference to the equilibrium phase diagram. It was found that the theoretical reduction limitation of total vanadium (T.V) in slag was decreased from 4.08 wt.% to wt. 0.86 wt.% when the Al content in alloy reached 2.0 wt.% at 1800 °C. The vanadium in slag was mainly presented in the form of MgV₃O₈ and coexisting with other phases of MgAl₂O₄, CaAl₂O₄, CaAl₄O₇, CaAl₁₂O₁₉. With the purpose of further decrease the high Al concentration in alloy and vanadium loss in slag, an improved SHS-EAH process was implemented by multi-stage gradient aluminum addition coefficient pattern, the average vanadium content in slag was reduced from 1.82 wt.% to 0.83 wt.%, while the aluminum content in FeV50 alloy was decreased from 1.5 wt.% to 0.4 wt.%. The SHS-EAH process was proved to be a better process with improved yield and quality for the preparation of ferrovanadium.     

Reaction behavior and wear properties of in-situ air plasma-sprayed Al2O3-TiB2 composite coatings

In this study, Al₂O₃-TiB₂ coating was successfully deposited on steel substrates by in situ plasma spraying (IPS) using H₃BO₃, Al, and TiO₂ reactants. Beside TiB₂ and Al₂O₃, Al₁₈B₄O₃₃ was formed as a by-product with ratio of about 13 wt%. The effect of milling time of reactant and the reaction behavior was also explored. Milling process for at least 10 h can promote efficiency of reaction and milling for efficient production of Al₂O₃-TiB₂ composite. Wear behavior was examined in terms of hardness, wear track width, and wear rate of the coatings with respective measured values of 797.6 HV, 1061.3 µm, and 4.2 × 10⁻³ mm³/N.m. Based on the FESEM observations, the thickness of abrasive coating was 417 µm, delamination and adhesion were the main wear mechanisms in Al₂O₃-TiB₂-coated specimens.