The working environment of agricultural knives is bad, which makes the knives wear out easily. A wear resistant layer of AlCoCrFeNi high entropy alloy (HEA) reinforced by tungsten carbide (WC) was prepared by laser cladding on one side of the cutting edge of a 65 Mn silage knife. Both the effects of WC addition on the microstructure and mechanical properties of AlCoCrFeNi (WC)_x (x = 0, 0.1, 0.2 and 0.3 in mass percentage) alloys were investigated. All experimental alloys displayed a crystalline structure of simple body centered cubic (BCC). The hardness of the cladding layer increases with the increase of WC content, and the hardness value enhances from 740 HV0.2 to 1060 HV0.2. A self-grinding edge was formed during working for the cladded knives. The cutting quality can be improved and the service life of agricultural knives can be increased meanwhile. The weight loss rate of untreated knives was about 2.64 times that of the cladded knives after a 76 h field experiment.

Al_1.8CrCuFeNi₂ high-entropy alloy coatings with different TiC contents were prepared using laser cladding. The effect of TiC on the microstructure, hardness and wear resistance of the coatings was investigated. It was found that the phase structure of the coating with 10 wt.% TiC was a single BCC phase with no other precipitated phase. When 20 wt.% TiC was added, the phase structure of the coating was a BCC phase and TiC phase. When the TiC content increased to 30 wt.%, more TiC-reinforcing phase was formed. With the increase in the TiC content, the hardness of the high-entropy alloy coating was enhanced and the wear loss clearly decreased, which was closely related to the change in the coating structure. The addition of TiC to high-entropy alloys plays the role of fine-grain strengthening and dispersion strengthening.

The working environment of agricultural cutting tools is poor, and the operational quality and efficiency are reduced after they become blunt. This study aimed to develop a high wear-resistant agriculture knife with a long life. A Ni–WC alloy, wear-resistant layer was prepared using laser cladding technology on one side of the cutting edge of a 65 Mn silage knife. A self-grinding edge was formed when the cladded knife was used, which improved the cutting quality and service life of the knife. The microstructure, phase, composition, and hardness distribution of the cladding layer were detected and analyzed. The impact toughness and wear resistance of the laser-cladded samples were analyzed, and the cladded knife was tested in the field. The results show that a cladded layer with a dense microstructure formed metallurgical bonds with the substrate. The microhardness was uniform across the cladded layer, and the average hardness of the micro Vickers was approximately 1000 HV(0.2), which was approximately three times the hardness of the substrate. The impact toughness and wear resistance of the coated knife were obviously higher than those of uncoated knives. The field tests showed that compared with a conventional 65 Mn knife, the self-grinding knife with laser cladding could maintain its sharp cutting shape after operation for 76 h, which greatly extended the service life of the knife. This study improved the service life of an agricultural cutting tool, which enhanced the cutting performance and efficiency at the same time.

The work aims to realize low-damage cutting of Alfalfa stalk. The self-sharpening blades of gradient material were prepared by 40 Cr steel, then heat-treating the flank surface by carbon-nitron-boronized with a rare elements catalysis technique. The biological characteristics of Alfalfa incision self-healing and regeneration process were analyzed in order to compare the cutting effects of different blades. After treatment with carbon-nitron-boronized with rare elements catalysis, the flank surface and tip point of blades were coated by boride layer and carbonitriding layer. The composition, microstructure and properties of the carbon-nitron-boronized layer demonstrated a gradient distribution state, and had good wear resistance. A kinetic model for the formation of the carbon-nitron-boronized layer was proposed. The initial stage of heat-treatment was mainly a carbonitriding process. When continuous and compact boride was formed on the surface, it was mainly boridized. The results of field experiment indicated that compared with the commercial blades, the self-sharpening blades have excellent properties as wear resistance and long service life. In addition, the cut damage caused by the self-sharpening blades was less, the self-healing and regeneration process of Alfalfa stalk was normal, and the regeneration duration was greatly shortened. The blades with carbon-nitron-boronized heat-treatment could form the self-sharpening characteristics, always maintaining the cutting sharpness, and realized the low-damage cutting of Alfalfa stalk.

The growing demand for low-frequency, broadband vibration and noise suppression technologies in next-generation mechanical equipment has become increasingly urgent. Effective negative mass locally resonant structures represent one of the most paradigmatic classes of acoustic metamaterials. Their unique elastic wave bandgaps enable efficient suppression of low-frequency vibrations, while inherent nonlinear effects provide significant potential for the design and tunability of these bandgaps. To achieve ultra-low-frequency and ultra-broadband vibration attenuation, this study employs Duffing oscillators exhibiting negative-stiffness characteristics as structural elements, establishing a bistable nonlinear acoustic-metamaterial mechanical model. Subsequently, based on the effective negative mass local resonance theory, the perturbation solution for the dispersion curves is derived using the perturbation method. Finally, the effects of mass ratio, stiffness ratio, and nonlinear term on the starting and cutoff frequencies of the bandgap are analyzed, and key geometric parameters influencing the design of ultra-low vibration reduction bandgaps are comprehensively investigated. Subsequently, the influence of external excitation amplitude and the nonlinear term on bandgap formation is analyzed using numerical computation methods. Finally, effective positive mass, negative mass, and zero-mass phenomena within distinct frequency ranges of the bandgap and passband are examined to validate the theoretically derived results. The findings demonstrate that, compared to a positive-stiffness system, the bandgap of the bistable nonlinear acoustic metamaterial incorporating negative-stiffness Duffing oscillators shifts to higher frequencies and widens by a factor of $\sqrt{2}$. The external excitation amplitude F changes the bandgap starting frequency and cutoff frequency. As F increases, the starting frequency rises while the cutoff frequency decreases, resulting in a narrowing of the bandgap width. Within the frequency range bounded by the bandgap starting frequency and cutoff frequency, the region between the resonance frequency and cutoff frequency corresponds to an effective negative mass state, whereas the region between the bandgap starting frequency and resonance frequency exhibits an effective positive mass state. Critically, the bandgap encompasses both effective positive mass and negative mass regions, wherein vibration propagation is suppressed. Concurrently, a zero-mass state emerges within this structure, with its frequency precisely coinciding with the bandgap cutoff frequency. This study provides a theoretical foundation and practical guidelines for designing nonlinear acoustic metamaterials targeting ultra-low-frequency and ultra-broadband vibration and noise mitigation.