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The theoretical research progress of Nano-ceramic ball milling technology is described, and the market application progress of Nano-ceramic ball mill mg technology m cement, metal mm mg, non-metallic powder and other muntries is emphatically introduced. Ceramic ball grinding technology can greatly reduce the consumption and power consumption of grind mg media, improve the partied size characteristics of grind mg products, reduce over grind mg, reduce iron pollution of moral surface, reduce the consumption of chemicals m the subsequent beneficiation process, improve the beneficiation mdex,and has a broad application prospect and development space. In the commotion of high pressure roller mill and ball mil or vertical mill unit, a new green grind mg process with low energy consumption and low cost with little or no steel balls is realized. [ABSTRACT FROM AUTHOR]

Mo2FeB2 based cermets with different w（Fe）/w（Ni）（10∶0, 7∶3, 5∶5, 3∶7） were prepared by the vacuum liquid phase sintering with MoB, Fe, Ni, and Cr powders as raw materials. The effects of w（Fe）/w（Ni） on the phase compositions, microstructures and mechanical properties of cermets were investigated. The results showed that the compositions of hard and binder phases of boride-based cermet with different w（Fe）/w（Ni） were different. When w（Fe）/w（Ni） of 3∶7, the hard phase was composed of Mo2NiB2 and Mo2FeB2; while in the cases of other w（Fe）/w（Ni）, the hard phase was Mo2FeB2. At 1 350 ℃, the microstructure of cermets was uniform and the size of pore is minimized, with the increase of sintering temperature, the hard-phase particles aggregated and the microstructure was not homogeneous, which led to the decrease of mechanical properties. After sintering at 1350 ℃ for 2 h, the hardness and bending strength of the obtained cermet（w（Fe）/w（Ni）=10∶0） reached the maximum, which were 82.1 HRA and 1 498.7 MPa respectively. Meanwhile, the analysis of fracture morphology revealed that a large number of dimples and rich tearing edges are closely related to the improvement of the bending strength of cermets. [ABSTRACT FROM AUTHOR]

The physical properties of cermet are closely related to the material composition and spatial structure, and its morphological distribution of composition phase have fractal characteristic. Based on the percolation theory and fractal theory, the fractal dimensions of the conducting phase were calculated through the binarization of the microstructure image analysis. The quantitative characterizations between the fractal dimension, microscopic morphology of the conducting phase and the critical exponent of percolation were established. The relationship between the microstructure and its electrical and thermal conductivity in the full composition range of Mo-ZrO2 cermet were studied. The results indicate that the fractal dimension of the conducting phase increases with the increase of the Mo volume fraction, and the relationship between conductivity and fractal dimension is consistent with the percolation theory. Based on the fractal dimension of the conducting phase, the General Effective Medium (GEM) equation was used to establish the electrical conductivity and the thermal conductivity models of cermet. By combining the quantitative analysis results of the microstructure and the percolation model of cermet, the gradient change of the macroscopic physical properties of the cermet can be effectively predicted. [ABSTRACT FROM AUTHOR]

BACKGROUND: LEWINNEK et al. proposed a “safety zone” concept for acetabular cup position [Abduction angle (40±10)°, anteversion angle (15±10)°]. Although this concept has been widely accepted, it has been lack of further biomechanical study regarding influence of acetabular prosthesis on acetabular bone and prosthetic stress distribution in the safety zone. OBJECTIVE: To investigate the stress distribution of the acetabular bone and cup (ceramic on ceramic versus metal on polyethylene) with regard to the Lewinnek safety zone using the three-dimensional finite element analysis method. METHODS: One healthy volunteer received CT scan. The three-dimensional geometric model of the pelvis was established. Eighteen kinds of different cup position model of hip replacement were established with regard to the Lewinnek safety zone. The stress distribution along the acetabular bone and the different implant materials were studied by means of applying 390 N force. The protocol was performed in accordance with the Declaration of Helsinki and the relevant ethical requirements of Sixth Affiliated Hospital of Xinjiang Medical University. RESULTS AND CONCLUSION: By applying finite element static vertical force, within the Lewinnek zone: (1): if the cup was positioned in 5° anterversion, 50° abduction (whether it was ceramic on ceramic or metal on polyethylene), the peak stress and the stress zone of the cup were smallest. Under the same anterversion and abduction, the peak stress of the cup did not change significantly. (2) With regard to the stress distribution of the head and liner, the peak stress and the stress zone of the head and the liner were smallest in the metal on polyethylene group, in which the stress was not affected by the position of the cup. (3) The results indicated that within the Lewinnek safety zone, if the cup was positioned in 5° anterversion, 50° abduction, the metal on polyethylene group had the advantage of having the smallest peak stress and the stress zone of the cup, head and the liner. Moreover, the stress was not affected by the position of the cup, and was significantly smaller than the ceramic on ceramic scheme, which can provide clinical reference. [ABSTRACT FROM AUTHOR]

BACKGROUND: Co-Cr ceramic alloys made by selective laser melting technology are widely used in the field of dental restoration, but the influence of selective laser melting technology on the bonding properties of Co-Cr ceramic alloys is still controversial. OBJECTIVE: To explore the metal-ceramic interface characteristics of dental Co-Cr alloy fabricated by selective laser melting. METHODS: Metal-ceramic specimens were prepared by selective laser melting and precision casting, respectively. Metal-ceramic bond strengths, interface characteristics, fracture analysis, microstructures and composition distribution of specimens were obtained with the aid of universal testing machine, metallographic microscope, scanning electron microscope coupled with energy disperse spectrometer. RESULTS AND CONCLUSION: (1) The metal-ceramic bond strengths of precision casting Co-Cr alloy was higher than that of selective laser melting Co-Cr alloy (P < 0.05). (2) Metallographic microscope showed that selective laser melting Co-Cr alloy had fine grains and a more uniform matrix. Precision casting Co-Cr alloy showed typical casting dendritic structure with coarse grains and a large number of island second phase structures. (3) Scanning electron microscopy showed that precision casting Co-Cr alloy had a thicker diffusion layer than the selective laser melting Co-Cr alloy at the metal-ceramic interface. (4) Scanning electron microscopy showed that the metal-ceramic specimens of precision casting Co-Cr alloy tended to cohesive fracture, and the metal-ceramic specimens of selective laser melting Co-Cr alloy tended to adhesive fracture. (5) The results showed that although the bonding strength of selective laser melting Co-Cr alloy was lower than that of precision casting Co-Cr alloy, the bonding strength of selective laser melting Co-Cr alloy could still meet the requirements of standard YY0621.1-2016. [ABSTRACT FROM AUTHOR]

Objective: To compare the effect and safety of zirconia all-ceramic restoration with metal ceramic restoration on the crown restoration of anterior teeth after lengthening. Methods: 80 patients(97 maxillary teeth in total) who underwent crown restoration after lengthening of anterior teeth were selected in our hospital from July 2016 to July 2018. The patients were divided into two groups by the random number table method. 40 patients(48 affected teeth) in the control group were repaired with metal porcelain, and 40 patients(49 affected teeth) in the observation group were repaired with zirconia porcelain.The results of dental restoration and periodontal restoration, the changes of sulcus bleeding index(SBI), mobility degree(MD) and plaque index(PI) as well as the occurrence of adverse reactions were compared between the two groups before and after treatment. Results: After treatment, the total effective rate in the observation group was significantly higher than that in the control group(87.76% vs. 70.83%, P <0.05). The patients in the observation group were significantly better than those in the control group in terms of marginal closeness, tooth breakage, tooth color and gingival health status(P <0.05). The SBI, MD and PI in the observation group was significantly lower than those of the control group(P <0.05).The incidence of adverse reactions in the observation group was significantly lower than that in the control group(P <0.05). Conclusion:Zirconium all-ceramic restoration for anterior crown extension is significantly better than metal-ceramic restoration, which can significantly improve the patients’ SBI, MD and PI with higher safety. [ABSTRACT FROM AUTHOR]

BACKGROUND: The dynamic computational model of artificial hip joints can effectively simulate the dynamic separation of femoral head and acetabular cup and explore edge contact between the head and cup. OBJECTIVE: To study the effect of the femoral head diameter on the edge load under dynamic micro-separation of hip joints, to provide a basis for biomechanical analysis of ceramic hip joints corresponding to early high wear problems caused by edge loading, and provide theoretical analyses for hip prosthesis design and clinical application. METHODS: Using the previously validated method, the dynamic model of artificial hip joint for edge contact based on Adams dynamic simulation software was used to predict dynamic micro-separation and edge contact force in the gait cycle of the hip joint. RESULTS AND CONCLUSION: (1) The maximum contact force of the edge loading under micro-separation of the cup and femoral head slightly reduced as the femoral head size increased. (2) The severity of edge contact was computed as the product of the edge contact force and its acting time. The severity parameter of φ36 mm head was 0.6% larger than that of φ28 mm one. The parameter of diameter 55 mm hip was 2.7% larger than that of φ28 mm and φ36 mm heads. (3) The change of the ceramic hip femoral head size has negligible effect on the edge loading. [ABSTRACT FROM AUTHOR]