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With the rapid development of wireless communication and Internet of things, intelligent products have been widely used in living and industrial places. The purpose of this paper is to develop an intelligent controller and intelligent lock cabinet for the monitoring of optical cable handover box. It can monitor the temperature, humidity, fire, flood, vibration and the identity of the personnel in and out of the optical cable box, and send the data information to the management server through wireless communication, so as to realize the purpose of monitoring and management of the optical cable box. The products under development include intelligent controllers, smart keys and electronic locks. The smart key is used in conjunction with the electronic lock.

This review summarizes the recent advances on the application of 57Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce2Fe14B, (Ce, Nd)2Fe14B and MM2Fe14B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting ΔE Q of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field B hf increases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the 57Fe Mössbauer spectrometry due to its high sensitivity. On this basis, the content, magnetic behavior, and magnetization of the REFe2 phase, the amorphous grain boundary (GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.

Palm oil empty fruit bunch (EFB) is a by-product produced during palm oil processing. In South East Asian countries, EFB is abundant and can be utilized as a renewable energy source. Cofiring of EFB with coal can be beneficial for preserving coal and reducing CO2 emission. However, EFB has some weaknesses in its properties such as; low bulk density, high moisture content, high alkaline contents, etc. Moreover, high amount of silicon and potassium in EFB tend to increase ash agglomeration which causes slagging and fouling in the equipment. In this study, hydrothermal treatment (HT) was employed to improve the physicochemical properties of the EFB by turning into biochar. Biochars are obtained after EFB is treated hydrothermally at a temperature range of 200-300 oC for 60 minutes were characterized for their proximate and ultimate compositions, mineral composition, calorific values, and ash fusion temperature. The analyses showed that fixed carbon increased while volatile matter decreased after HT. These changes were more prominent with increasing reaction temperature. The calorific values of EFB increased from 19.05 MJ/kg to 29.31 MJ/kg after HT at 300 oC. The biochar was then mixed with coal at different ratios (1:1, 1:2, and 2:1) for cofiring. The results showed that the energy densification increased with increasing reaction temperature. XRF results showed that the contents of Na, K and Si in EFB decreased after HT, resulting in the increased ash melting temperature. Consequently, the fouling and agglomeration potential could be reduced. The optimum ratio for cofiring between biochar and coal was found to be 2:1, as the fouling and slagging indices were lowest. It can be concluded that HT is a promising method for upgrading EFB as a feedstock for cofiring with coal.

Since the 1980s, Nd–Fe–B with largest energy product (BH)max approaching the theoretical limit has become the landmark of permanent magnetic material. The application spectrum for Nd–Fe–B continues to expand over time both in the industrial and commercial sectors, which leads to growing research interests for solving the long-standing drawbacks of Nd–Fe–B, i.e., poor corrosion resistance, low coercivity, high Dy/Tb and low La/Ce/Y consumption. Concerning the above obstacles, we aim to present the novel grain boundary restructuring (GBR) approach, from GB design, processing, to structure evolution and property evaluation with a focus on the corrosion and coercivity mechanism of the restructured 2:14:1-typed magnets. Starting with an introduction to the fundamental of GBR, two representative examples, high-electrode-potential (Pr, Nd)32.5Fe62.0Cu5.5 and low-melting-point Dy71.5Fe28.5, are given with detailed descriptions of the advantages of GBR to enhance the intrinsic anti-corrosion stability and to strengthen the coercivity at low Dy consumption. Microstructure–property correlations are established to understand the critical importance of regulating the restructured GB phase to maximize the all-round performance of the 2:14:1-typed permanent magnets. Aiming at sustainable and balanced development of rare earth (RE) industry, the proceeding section proposes new prototypes of La–Ce and Y–Ce co-substitutions with dual benefits of stabilizing the 2:14:1 tetragonal phase and strengthening the intrinsic hard magnetism. The findings of additional REFe2 intergranular phase delight that the GBR approach also opens up a new horizon of research and application to develop high-performance La/Ce/Y-rich permanent magnets with deliberately tailored GB phase.

Refinement of the FePt grain size for heat-assisted magnetic recording (HAMR) media was explored by utilizing high melting point metals Pt and W as seed layers. Unlike the W, the Pt seed layer promotes a good epitaxial growth and leads to a higher degree of L10-ordering in FePt films. It also substantially refines the FePt grains from big islands into smaller particles. For the FePt-C nanogranular film, the Pt seed layer improves the wettability and favors a single-columnar growth. Thus, the Pt seed layer provides a new valid approach to optimize the microstructure and magnetic properties for next-generation FePt-based HAMR media.

The grain boundary diffusion process (GBDP) is effective to enhance coercivity of the single-main-phase (SMP) RE2Fe14B (rare earth (RE)) magnets through forming magnetic hardening shells surrounding the hard grain cores. Here, the GBDP was applied to the multi-main-phase (MMP) (Nd, Pr)22.3Ce8.24FebalM1.0B1.0 (wt.%) magnets prepared by sintering the mixture of Ce-free and Ce-containing 2:14:1 powders, which have shown superior magnetic properties, especially coercivity, to the SMP ones at the same average composition. The remanence of the (Nd, Pr)H x diffused magnets increases gradually with the increase of diffusion temperature from 480 to 880 °C, the coercivity, however, slightly decreases. The highest (BH)max of 350.1 kJ m−3 is achieved when diffusing at 680 °C, which is 9.2% higher than 320.7 kJ m−3 for the as-prepared magnet. The remanence increment is due to the diffusion of Nd/Pr into the 2:14:1 phase grains, enlarging the intrinsic saturation magnetic polarization. The slight coercivity reduction is due to the gradual homogenization of RE distribution within the 2:14:1 grains of the undiffused parts, i.e. approaching the 'close to equilibrium (or SMP)' state, which offsets the positive contributions from the enrichment of Nd/Pr in the Ce-rich 2:14:1 phase and the formation of continuous RE-rich intergranular phase. These findings suggest that the GBDP effect on coercivity of the MMP Nd–Ce–Fe–B magnets is distinctly different from the SMP ones, and that the chemical heterogeneity should be carefully controlled to improve the magnetic properties of such high cost-performance permanent magnets.

Magnetic transitions and the magnetoresistance effect of the HfFe6Ge6-type Y1−xLaxMn6Sn6 (x = 0.1 and 0.2) compounds have been investigated in the temperature range 5–385 K. The samples display an antiferromagnetic behaviour in the whole magnetic ordering temperature range, and their Neel temperature is 309 K and 323 K for x = 0.1 and 0.2, respectively. The metamagnetic transition from antiferromagnetism to ferromagnetism can be induced by an applied field. The metamagnetic transition field varies from 20 kOe at 5 K to 4 kOe at 300 K. The giant magnetoresistance effect is observed with the metamagnetic behaviour, such as −10.4% at 245 K for x = 0.1 under 50 kOe. Interestingly, the positive magnetoresistance for x = 0.2 appears below 110 K.

Magnetic transitions and the magnetoresistance (MR) effect of the HfFe6Ge6-type Y1-xCexMn6Sn6 (x=0.1-0.3) compounds have been investigated in the temperature range of 5-385 K. Y0.9Ce0.1Mn6Sn6 and Y0.825Ce0.175Mn6Sn6 show antiferromagnetism and Y0.7Ce0.3Mn6Sn6 undergoes an antiferromagnetic (AFM) to ferrimagnetic (Fi) transition with increasing temperature. The metamagnetic transition from helical antiferromagnetism to ferrimagnetism can be also induced by an applied field for those compounds. The metamagnetic transition field decreases with increasing Ce content, such as from 25 kOe for x=0.1 to 11 kOe for x=0.3 at 5 K. The giant MR (GMR) effect for Y1-xCexMn6Sn6 (x=0.1-0.3) is observed with metamagnetic behaviour, such as -37% at 5 K under a field of 50 kOe for the compounds (x=0.175 and 0.3). It is found that the MR behaviour for Y0.7Ce0.3Mn6Sn6 in the Fi state follows the magnetic-field power law MR proportional to-H-q at a fixed temperature, and obeys the relationship MR=-[alpha+beta/(T+gamma)] under a fixed magnetic field.

In this paper, the frictional temperature field and its relationship to the transition of wear mechanisms of steel 52100 during dry sliding were studied by wear testing, SEM observations of worn surfaces and particles. Computer simulation of the temperature field in a surface layer during sliding wear was based on a mathematical model of frictional temperature field which itself was based on the law of heat conduction. The results of computer simulation for thermometric data, which were real-time recorded by a thermal video system, show that there was an ideal fit between the measured data and calculated curve. On the basis of analysing the relationship between the transition from mild wear to severe wear and the temperature field in surface layers during sliding of the steel, a new concept is put forward that the lower heat effect corresponds to mild wear and the higher heat effect corresponds to severe wear. The value of Tb corresponding to the transition of wear mechanisms of steel 52100 is about 200 °C.

Diffusing heavy rare earth elements along the grain boundaries (GBs) for Nd2Fe14B-type sintered magnets serves as an effective method to enhance coercivity and to minimize remanence loss simultaneously. Considering the texture anisotropy of Nd-rich GB phases, the coercivity incremental difference by diffusing DyHx fine powders along or perpendicular to the easy axis (c-axis) has been investigated. The coercivity increases more rapidly to 20.61 kOe (5.76 kOe higher than that of the as-sintered state) when diffusing along the c-axis than that diffusing perpendicular to c-axis (18.85 kOe, 4.00 kOe higher than the as-sintered state). Microstructural investigation reveals that Dy diffuses more easily towards the magnet inner part when treating along the c-axis than that for the perpendicular case due to the anisotropic distribution of the Nd-rich phase. This is verified by a higher Dy content at equivalent diffusing depth and a much deeper final diffusion distance. The local Dy-containing fractions with a stronger anisotropy field are richer for the magnet treated along the c-axis, leading to the much rapider coercivity enhancement. This work reveals that diffusion heavy rare earth along the c-axis is more effective to enhance coercivity for aligned Nd–Fe–B sintered magnets.

The compressive pre-stress induced magnetostriction jump effect of an [110] oriented TbDyFe crystal is simulated by tracking the initial redistribution of magnetic domains and their volume fraction evolutions under external magnetic fields. Through searching for the free energy minima within both (110) and (110) planes, it is found that the axial compressive pre-stress not only switches magnetizations of the 35° domains toward the perpendicular plane, but also switches magnetizations of the 90° domains approaching the [110] direction. When increasing the stress magnitude, the volume fraction for 35° domains decreases and the one for the [110] domain increases rapidly. However, the volume fraction for the four 90° domains within the perpendicular plane first increases to a maximum under a certain stress magnitude and further decreases. The stress-induced anisotropy thereafter changes the volume fraction evolutions during the magnetization process, which explains well the magnetostriction jump effect.

The magnetomechanical performance of ferromagnets is strongly sensitive to their initial magnetic states. In this work, magnetomechanical properties of the 1 1 0 oriented crystals Tb0.36Dy0.64(Fe0.85Co0.15)2 with different initial magnetic states induced by field annealing have been studied. Young's moduli and damping capacity were calculated from stress–strain curves taken by quasi-static measurements. The sample became 'harder' after perpendicular magnetic annealing, possessing much larger Young's modulus than the untreated one. In addition, the maximum damping capacity ΔW/W for the magnetically annealed rod reached 1.176 at a stress magnitude of 21.2 MPa, both of which were higher than that of the untreated sample. The variation of Young's moduli and damping capacity can be explained by the magnetic domain switching process and movements of non-180° domain walls.