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HighlightsThe thermal reaction between Glycyrrhiza uralensis and metal was analyzed via thermogravimetry.The wear characteristics of three common blade metals were studied under laboratory conditions.The wear mechanisms on the blades by different parts of Glycyrrhiza uralensis were analyzed.Thermal oxidation and element transfer occurred during the wear of Glycyrrhiza uralensis and metals.Abstract. To investigate the wear of metal blades when kneading and crushing total mixed ration (TMR) forage grass, the chemical composition of licorice (Glycyrrhiza uralensis) was determined using hydrochloric acid hydrolysis, titration, and Kjeldahl nitrogen determination, and the thermal stability of G. uralensis was analyzed with thermogravimetry (TG). Blades made of spring steel (65Mn), mold steel (Cr12MoV), and tool steel (9CrSi) were selected for the wear tests. The wear mechanisms of the cork and wood layers of G. uralensis on blades were explored via reciprocating friction. The elemental content and worn surface morphology of the blades were analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES), three-dimensional morphology, scanning electron microscopy, and X-ray energy spectrum analysis. Results showed that the wear on the blades was mainly abrasive, fatigue, and adhesive wear. Comparison of the wear of the G. uralensis cork and wood layers with that of the three blade types revealed that the coefficient of friction was smallest for the 65Mn blades, at 0.20 and 0.75, respectively, for the cork and wood layers. The combination of pyrolysis of G. uralensis with a change in the atomic content on the wear surfaces of the blades indicated that the wear process of the blades was accompanied by thermal oxidation. Damage to the blades by the G. uralensis wood layer was more serious than damage by the cork layer. The surface roughness and the depth of the wear scars for the G. uralensis wood layer on 65Mn blades were 0.085 µm and 0.427 µm, respectively, which were lower than the wear parameters for the Cr12MoV and 9CrSi blades under the same conditions. Therefore, 65Mn blades have good wear resistance and plastic resistance under the same wear condition. This study provides a reference for blade selection for cutting of TMR forage materials. Keywords: Blade, Glycyrrhiza uralensis, Surface roughness, Wear resistance, Weightlessness rate.

During granulation, a serious wear problem may be found in flat die as a key component of a flat die pellet mill. Specific to this problem, Glycyrrhiza uralensis was selected as the wear-causing material to investigate the wear mechanism of the flat die. Additionally, carburizing steel (20Cr and 20CrMnTi) and stainless steel (4Cr13) commonly used in flat die were adopted to conduct wear tests. To explore the influence of Glycyrrhiza uralensis powder and rods on friction and wear properties of the above three types of steel materials, a CFT-I general-purpose tester for surfaces was applied under dry friction conditions. Moreover, x-ray diffractometer (XRD), three-dimensional profilometry, scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) were used to analyze the phase compositions, surface morphologies, and elementary compositions of the samples. As demonstrated by relevant results, the influence of Glycyrrhiza uralensis on the flat die is primarily embodied in abrasive, adhesive, and fatigue wear, and a thermal oxidation reaction occurs on the surface of the flat die. By comparing the wear conditions of the three steel materials between the powder and rods of Glycyrrhiza uralensis, it is found that flat die damages caused by glycyrrhiza rods are more severe than those of its powder. Additionally, the lowest friction coefficients are generated by 20CrMnTi, which are 0.40 and 0.88, respectively. In terms of the mean wear depth, its values are 1.2 and 2 μm, which are below those of 20Cr and 4Cr13. The results herein reveal that flat die made of 20CrMnTi have excellent wear and ductile fracture resistance characteristics. Hence, this study may provide a theoretical guide for selecting flat die materials.

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