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In this paper, TC4/AZ91D bimetallic composites has been prepared by liquid–solid compound casting process adapting various thickness of Cu coating. The effects of Cu coating thickness on the evolution of interface microstructures and joint mechanical properties are investigated. The results indicate that metallurgical bonded joints are obtained with Cu coating thickness ranging from 36.7 to 51.4 μm. With the increase of Cu coating thickness, the interface microstructure evolves from δ-Mg + Mg2Cu eutectic structure to Mg–Cu intermetallic compound (IMC) Cu2Mg + Mg2Cu and Mg–Al–Cu ternary intermetallic compound. The calculation results of formation enthalpy and chemical potential of Mg–Al–Cu system suggest that Cu element prefers to react with Mg element and formed Mg–Cu IMC. In particular, when Cu coating thickness reaches 36.7 μm, the average shear strength of the bimetal reaches a maximum of 65.3 MPa. Further increasing Cu coating thickness leads to the generation of thick Mg2Cu IMC layer and Mg2Cu + Cu2Mg mixed IMC layer which are proved to be harmful to the shear strength of TC4/AZ91D bimetals. All the fracture surfaces of the bimetallic composites exhibite to have a brittle fracture morphology. However, the fracture location is different with each other. For Cu coating thickness of 36.7 μm, the interface fractures at the δ-Mg + Mg2Cu eutectic structure, while the interface fractures at the Cu2Mg + Mg–Al–Cu ternary intermetallic layers when Cu coating thickness is 44.2 μm and 51.4 μm.

Aluminum (Al)/AZ91D magnesium (Mg) alloy bimetals, i.e., AZ91D magnesium alloy parts with Al coatings, were produced by pouring liquid Mg alloy, at temperatures of 933, 963, 993 and 1023 K, into molds with an arc-sprayed Al coating deposited. It was shown that an interface zone was generated in the Al/AZ91D bimetal produced by this novel solid–liquid compound casting technique, when the pouring temperature wasn't lower than 963 K. A mixing zone, composed of Al, alumina and MgAl2O4, was formed in the bimetal cast at 933 K. When the pouring temperature was increased from 963 to 1023 K, the interface zone mainly comprising the Al–Mg intermetallic compounds increased in thickness, and the γ-Al12Mg17 intermetallic compounds in this zone tended to grow toward the Mg alloy side. The obtained interface zones of the Al/AZ91D bimetals showed greater microhardness than the substrate and the coating metal. At a pouring temperature of 993 K, the Al/AZ91D bimetal had the thinnest interface zone without any untransformed Al pieces and thread-like MgAl2O4, leading to the highest shear strength of 25 MPa. Since the expansion of the interface zone increased the possibility of brittle fracture, an excessive increase in the pouring temperature did not necessarily improve the adhesive strength between the as-cast AZ91D and the arc-sprayed Al coating.

The solid–liquid compound casting of Mg-AZ91D and Ti-TC4 alloys was developed by using pure Ni electro-deposited coating. The pouring temperatures of 660 ℃, 690 ℃, 720 ℃ and 750 ℃ were chosen to investigated the effects of casting temperatures on microstructural evolution, properties, and fracture behaviors of Ni-coated TC4/AZ91D bimetals by the solid–liquid compound casting (SLCC). The scanning electron microscopy (SEM) and the energy dispersive spectroscopy (EDS) results showed that the interfacial zone mainly composed of nickel, Mg2Ni and Mg-Al-Ni in the bimetals cast at 660 ℃. As the pouring temperature was increased to 750 ℃, the width of the interface zone, which mainly composed of δ(Mg), Mg2Ni, Mg-Al-Ni, Mg3TiNi2 and Al3Ni, gradually increased. The microhardness tests showed that the micro-hardness of the interface zone was smaller than that of TC4 substrate but larger than that of the cast AZ91D matrix. At the pouring temperature of 720 ℃, the Ni-coated TC4/AZ91D bimetals had the most typical homogeneous interface, which had granular Mg-Al-Ni ternary phase but no ribbon-like Al3Ni binary phase, and achieved the highest shear strength of 97.35 Mpa. Meanwhile, further fracture behavior analysis showed that most fracture failure of Ni-coated TC4/AZ91D bimetals occurred at the Mg2Ni + δ(Mg) eutectic structure and Al3Ni hard intermetallic.

The reduction in sound pressure level is the focus of noise reduction in construction machinery, but the sound quality parameters can better describe the operator’s subjective perception of noise. This paper proposes a sound quality control method for the cab, which is based on complementary ensemble empirical mode decomposition for signal decomposition and reconstruction and an adaptive control algorithm error filter. Firstly, a subjective and objective prediction model was created to identify the target parameters for the sound quality control in the cab. Secondly, the noise was reconstructed based on a complementary ensemble empirical mode decomposition method, thus evaluating the influence of each component on the sound quality and determining the frequency interval. Lastly, the active sound quality control was completed based on the variable step size filter-error least mean square algorithm. The experiments were performed in the cab of a mini-excavator to verify the method’s effectiveness. It was verified that the loudness peak drops by 0.95 sones under stationary idle working conditions. The results demonstrate that the above methods play a guiding role in the actual application of sound quality control for the cab of construction machinery.

The permissioned blockchain has attracted the attention of multiple industries like the supply chain due to its decentralization and data tamper resistance. In these industries applications, the permissioned blockchain maintained by multiple participants often has a large number of nodes. The PBFT consensus is commonly used in the permissioned blockchain, but it requires a large amount of message transmission to reach consensus, resulting in poor scalability. In this paper, we propose DP-Hybrid, a novel two-layer consensus protocol, to reduce the communication costs and improve scalability. Specifically, nodes use PBFT to establish K autonomous systems at the bottom layer, and then participate at the top layer with Constrained PoW consensus protocol. DP-Hybrid reduces the communication costs from PBFT’s \(O(N^2)\) to \(O(N^2/K^2)\). The experiment results show that DP-Hybrid’s throughput is always about 10 times that of PBFT when the number of nodes increases.

In this study, the Ni coated TC4 alloy was treated by vacuum heat treatment to study the effect of induction heat treatment on the diffusion process and the formation of intermetallic compounds at the interface between Ni coating and TC4 substrate to avoid oxidation on the surface. The results by induction heat treatment were compared with that by resistance heat treatment. The effects of heating temperature and heat treatment time of the induction heat treatment were discussed in detail. The formations of intermetallic compounds including TiNi3, TiNi, and Ti2Ni were analyzed. With the increase of heat treatment time, TiNi3 phase is decomposed completely, and the intermetallic compounds at the surface of TC4 alloy are TiNi and Ti2Ni. The Gibbs free energies of intermetallic compounds in Ti-Ni system were calculated, and the eddy current produced by induction heat treatment has an important influence on the formation of intermetallic compounds. The Ni coated TC4 alloy after induction heat treatment for 1050 °C and 60 min shows to have a better tribological property. By conducting induction heat treatment, TiNi phase at surface of TC4 alloy can be obtained which is helpful for further applications of Ti alloy under mechanical contacting conditions.

A novel technique combining solid&ndash, liquid compound casting (SLCC) with arc spraying was designed to manufacture the arc-sprayed Al/AZ91D bimetals with a Zn interlayer. The Al/Mg bimetal was produced by pouring the AZ91D melt into the molds sprayed with Al/Zn double-deck coating, during which the arc-sprayed Zn coating acted as the interlayer. The effect of the Zn interlayer on microstructures, properties, and fracture behaviors of arc-sprayed Al/AZ91D bimetals by SLCC was investigated and discussed in this study. The optimal process parameter was acquired by analyzing the results from different combinations between the arc-spraying time of the Zn coating (10, 18, and 30 s) and the preheat time of the Al/Zn double-deck coating (6 and 12 h). The interfacial microstructures of the arc-sprayed Al/AZ91D bimetals with a Zn interlayer could be approximately divided into two categories: One was mainly composed of (&alpha, Mg + Al5Mg11Zn4) and (&alpha, Al + Mg32(Al, Zn)49) structures, and the other primarily consisted of (&alpha, Mg + Al5Mg11Zn4), (MgZn2 (main) + &beta, Zn), and (&beta, Zn (main) + MgZn2) structures. In the interface zone, the (&alpha, Mg + Al5Mg11Zn4) structure was the most abundant structure, and the MgZn2 intermetallic compound had the highest microhardness of 327 HV. When the arc-spraying time of the Zn coating was 30 s and the preheat time of the Al/Zn double-deck coating was 6 h, the shear strength of the arc-sprayed Al/AZ91D bimetal reached 31.73 MPa. Most rupture of the arc-sprayed Al/AZ91D bimetals with a Zn interlayer occurred at the (&alpha, Mg + Al5Mg11Zn4) structure and presented some typical features of brittle fracture.

The austempered ductile iron was austenitized at 900 &deg, C for 1 h and quenched in an isothermal quenching furnace at 380 &deg, C and 280 &deg, C, respectively. This paper aims to investigate the effects of bainite on wear resistance of austempered ductile iron (ADI) at different loads conditions. The micro-structure and phase composition of ADI was characterized and analyzed by metallographic microscope (OM), X-ray diffractometer (XRD) and scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The results showed that the volume fraction of retained austenite in ADI is reduced with the increase of austenitizing temperature. Meanwhile, the two kinds of ADI samples showed varied wear resistance when they were worn at different loads conditions. For wearing at a load of 25 N, the wear resistance of ADI mainly depends on matrix micro-hardness. Thus, ADI with lower bainite structure has higher hardness and leads to better wear resistance. When wearing at a load of 100 N, the increase of micro-hardness of upper bainite was significant. As a consequence, upper bainite showed superior friction and wear behavior. It was also found that the form of wear behavior of ADI changed from abrasive wear to fatigue delamination as the wear load increased from 25 N to 100 N according to the observation on worn surface.

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of &alpha, Mg and an eutectic structure (&alpha, Mg + MgZn). The intermediate layer was comprised of an eutectic structure (&alpha, Mg + MgZn), and the layer adjacent to 45 steel consisted of &alpha, Mg and FeAl3. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from &minus, 1.493 V to &minus, 1.143 V and corrosion current density changed from 3.015 &times, 10&minus, 5 A/cm2 to 1.34 &times, 7 A/cm2 implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D.

A radial shearing (RS) interferogram obtained by the carrier fringe method is essentially the combination of radial and lateral shearing. The previous phase reconstruction algorithm neglects the effect of lateral shearing on the obtained RS interferogram. A mathematical formula for wavefront reconstruction from an RS interferogram is deduced. If the phase difference of the tested wavefront phase, the RS ratio s, and the laterally sheared amount x(0) in the x direction and y(0) in the y direction, respectively, have been determined, the tested wavefront phase can be precisely reconstructed using this formula. The result of simulation analysis and experiment shows that the formula is correct and more accurate.