可编程快速充电管理芯片MAX712/MAX713及其应用

本文介绍MAXIM公司生产的可编程电池充电管理芯片MAX712/MAX713,利用MAX712/MAX713系列芯片及简单外围电路可设计低成本的单多节镍氢电池或镍镉电池充电器,非常适用于便携式电子仪器的紧凑设计。本文将在介绍MAX712/MAX713芯片的特点、功能的基础上,给出典型充电电路的设计方法及应用该充电芯片设计便携式仪器的体会。     

MAX相陶瓷强化方式及机理研究进展

MAX相陶瓷兼具金属和陶瓷的优良性能,在航空航天、高铁、核工业等许多高新技术领域拥有巨大的应用潜力。但是,MAX相的强度和硬度偏低,这限制了其在实际工程中的应用。本文总结了MAX相陶瓷材料的强化方式及机理,重点介绍了固溶强化、第二相颗粒强化和织构强化等强化方式对MAX相陶瓷力学性能的影响。最后,展望了MAX相材料强化的研究前景。为该材料在实际工程中应用提供了重要的参考价值。     

浅谈导向钻井系统在延长油矿浅井定向施工中的应用

本文通过对延长油矿7219平台、2042平台、注417平台、番1006平台单弯导向24口井试验应用,分析了直螺杆与单弯定向的优缺点,进而提出单弯导向是浅井定向施工中提高定向准确性的一种比较好的方法,可以推广应用。     

三元层状可加工导电MAX相陶瓷研究进展

三元层状可加工导电陶瓷是一类键合具有明显各向异性的层状碳化物或氮化物,它通常又被称为MAX相陶瓷。MAX相陶瓷具有优良的可加工性,良好的导电、导热能力,可观的高温强度,同时还具有良好的热稳定性、抗氧化性、抗热震性和耐腐蚀性能。本文介绍了MAX相陶瓷的结构、性能以及制备方法和应用前景。     

三元层状结构MAX相陶瓷材料的制备技术及其研究发展现状和发展趋势

三元层状结构陶瓷材料主要是指M_n+1AX_n相,三元层状结构MAX相陶瓷材料具有金属的特性还具有陶瓷的特性,三元层状结构MAX相陶瓷材料具有较高的力学性能,良好的耐磨损性能和良好的耐腐蚀性能,并具有良好的抗高温氧化性能等,还具有良好的可加工性能。三元层状结构MAX相陶瓷材料主要有Ti₃SiC₂,Ti₄SiC₃,Ti₃AlC₂,Ti₂AlC,Ti₄AlN₃和Ti₂AlN等。本文主要叙述三元层状结构MAX相陶瓷材料的制备技术,物相组成,显微结构,力学性能和耐磨损性能,耐腐蚀性能和抗高温氧化性能以及其他性能等。并叙述三元层状结构MAX相陶瓷材料的研究发展现状和发展趋势。并对三元层状结构MAX相陶瓷材料的未来研究发展趋势和发展方向进行分析和预测。     

MAX相中的晶体结构缺陷:研究现状与发展方向

MAX相陶瓷兼具陶瓷和金属的优良特性,比如高的比模量和比强度、优异的化学稳定性和加工性能、良好的抗损伤容限及导电导热性等,这使得该类陶瓷成为一种非常有前景的高温结构材料。目前,已至少有2部专著、6篇综述详细介绍了MAX相的制备方法、性能特征等。晶体结构缺陷是影响材料性能的主要因素之一。为了更有效地设计和调控材料的性能,有必要对其晶体结构和缺陷有清楚的认识。然而,由于缺乏系统的总结,对MAX相的缺陷研究和认识还有很多不足之处,有些理解甚至是错误的。为了深入理解MAX相中的缺陷特征及其对性能的影响,本文概述了近20多年来MAX相陶瓷中晶体缺陷的研究进展。     

磁性MAX相陶瓷研究进展

MAX 相陶瓷综合了陶瓷材料和金属材料的诸多优点,包括低密度、高模量、良好 的导电/导热性能、优异的抗热震性能、抗损伤性能以及优良的抗高温氧化性能等,已经获得研 究者的广泛关注。近年来,带有磁性的 MAX 相陶瓷相继被发现并被成功制备。本文结合国内 外在该领域的发展现状,重点介绍当前已被发现磁性 MAX 相陶瓷的合成和磁性特性。     

高耐热性的聚醚醚酮/聚酰亚胺复合树脂新品上市

<正>英国威格斯(VICTREX)发布了由该公司的聚醚醚酮(VICTREXPEEK)和沙特阿拉伯基础创新塑料公司的热可塑性聚酰亚胺(Extem)组成的复合材料"MAX"系列。与标准等级的PEEK相比,MAX在     

高温下性能得到改善的共聚物

据"Modern Plastics,2008,(5):28"报道,MAX系列产品是受专利保护的一类共混聚合物,它兼具好的高温力学性能和尺寸稳定性。MAX系列产品具有PEEK(聚醚醚酮)和Sabic创新塑料公司Extem UH系列TPI(热     

MAX相及喷涂法制备MAX相涂层

MAX相作为新型的三元层状陶瓷材料,兼具陶瓷材料和金属材料的优良性能。性能的优异性使得其在诸多领域都有应用潜力,拥有广阔的使用前景。本文主要介绍该材料的结构、性能、制备方法以及利用喷涂法制备MAX相涂层的最新研究进展。     

MAX phase Zr2SeC and its thermal conduction behavior

The elemental diversity is crucial to screen out ternary MAX phases with outstanding properties via tuning of bonding types and strength between constitutive atoms. As a matter of fact, the interactions between M and A atoms largely determine the physical and chemical properties of MAX phases. Herein, Se element was experimentally realized to occupy the A site of a MAX phase, Zr₂SeC, becoming a new member within this nanolaminated ternary carbide family. Comprehensive characterizations including Rietveld refinement of X-ray Diffraction and atom-resolved transmission electron microscopy techniques were employed to validate this novel MAX phase. The distinct thermal conduction behaviors emerged are attributed to the characteristic interactions between Zr and Se atoms.     

Intrinsic Mechanical Properties of 20 MAX‐Phase Compounds

The intrinsic mechanical properties of 20 MAX‐phase compounds are calculated using an ab initio method based on density functional theory. A stress versus strain approach is used to obtain the elastic coefficients and thereby obtain the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio based on the Voigt–Reuss–Hill (VRH) approximation for polycrystals. The results are in good agreement with available experimental data. It is shown that there is an inverse correlation between Poisson's ratio and the Pugh ratio of shear modulus to bulk modulus in MAX phases. Our calculations also indicate that two MAX compounds, Ti₂AsC and Ti₂PC, show much higher ductility than the other compounds. It is concluded that the MAX‐phase compounds have a wide range of mechanical properties ranging from very ductile to brittle with the “A” in the MAX phase being the most important controlling element. The measured Vickers hardness in MAX compounds has no apparent correlation with any of the calculated mechanical parameters or their combinations.     

Theoretical predictions on temperature-dependent strength for MAX phases

MAX phases have great application potential in high-temperature fields due to their unique combination of ceramic and metallic properties. In this work, a physics-based theoretical model is developed for the prediction of temperature-dependent strength of MAX phases, based on the force-heat equivalence energy principle. The quantitative relationship between the strength, Young's modulus, temperature, and melting point is revealed by the proposed model. Through the comparison between theoretical predictions of strength and available experimental results from the literature, the model is proved to be efficient in predicting the strength of MAX phases at high temperatures. Since the melting point and Young's modulus of material can be easily obtained, the proposed theoretical model provides a convenient and feasible method for predicting the temperature-dependent strength of MAX phases.     

Analytical model for strength of MAX phases considering high-temperature oxidation and plastic deformation

As a promising high-temperature material, MAX phases have attracted much attention owing to their combined merits of metals and ceramics. In this study, a temperature-dependent analytical model for prediction of the strength of MAX phases considering high-temperature oxidation and plastic deformation was proposed. A relationship among the strength, Young's modulus, strain-hardening exponent, crack size, and temperature was established. The accuracy of the model was verified by a comparison between the model predictions and available experimental data. The proposed analytical model can provide a straightforward and effective way to predict the strength of MAX phases over a wide range of temperatures. Moreover, the quantitative effects of oxidation time, strain-hardening exponent, and Young's modulus on the strength, as well as their evolution with temperature, were analyzed. The findings of this study would be useful for the high-temperature strength prediction and design of MAX phase materials.     

A facile pot synthesis of (Ti3AlC2) MAX phase and its derived MXene (Ti3C2Tx)

Various processing techniques reported in the literature for synthesizing the Ti₃AlC₂ MAX phase involve high calcination temperature, expensive equipment, and inert environmental requirement. Here, we report a cost-effective, solid-state, single-step synthesis route of the Ti₃AlC₂ MAX phase. Optimizing the stoichiometry of the precursors and controlling the thermal treatment, the desired MAX phase has been attained, as confirmed by XRD analysis. Further, Ti₃C₂T_x (where, T_x: O, OH, F functional groups) MXene was prepared from this one-pot synthesized MAX phase. FESEM, TEM, and Raman spectroscopy were used to ensure that the hexagonal structure of the MAX phase was retained in as-synthesized MXene. Further, XPS was employed to detect the presence of surface functional groups (-O, –OH, and –F) on the MXene surface. UV–vis spectroscopy shows a strong absorption peak in the NIR region.     

Synthesis and enhanced mechanical properties of compositionally complex MAX phases

A novel strategy of fabricating compositionally complex MAX phases was successfully developed. Multicomponent 413 MAX phase solid solutions (Ti_0.36Nb_0.27Ta_0.37)₄AlC_2.8 and (Ti_0.28Nb_0.26Ta_0.28V_0.18)₄AlC_2.9 simultaneously containing 3 and 4 transition-metal elements at M site were experimentally synthesized via hot pressing equimolar mixture of 211 type MAX phase powders. By elemental analysis and structural characterization, it can be verified that those uniform compositionally complex solid solutions can be obtained only in the presence of Cr₂AlC in raw powders. Those compositionally complex MAX phase solid solutions exhibit typical layered structures with distinct elongated grains. This discovery further enriches the MAX phases family and provide a new avenue for tailoring the properties of these materials. MAX phase composites containing around 87.5 vol.% (Ti_0.36Nb_0.27Ta_0.37)₄AlC_2.8 exhibit a high flexural strength of 720 MPa and a high fracture toughness of 9.5 MPa m^0.5.     

Oxidation behaviors of compositionally complex MAX phases in air

The oxidation behaviours of a newly synthesized MAX phase composite mainly containing a multi-component 413 MAX phase with Ti, Nb and Ta equally and evenly distributed at M site were investigated at 1000–1400 °C in air. Results indicated that the multi-component MAX phase exhibited superior oxidation resistance compared with traditional monolithic 413 MAX phases such as Nb₄AlC₃ and Ta₄AlC₃. Dense and passivating Al₂O₃ layers that formed at the interfaces between the substrate and the oxidation scale is the origin of the high oxidation resistance. The presence of Cr–Al alloy phases is essential for the formation of protective Al₂O₃ scale.