Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely us...Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).展开更多
目的研究成纤维细胞生长因子18(FGF18)是否能诱导体外分离培养的人牙龈成纤维细胞(HGFs)向成骨样细胞分化,并探究其成骨机制。方法组织块法分离培养HGFs并鉴定。取第3代HGFs,分为实验组和对照组。实验组加入FGF18和L-DMEM、对照组加入L-...目的研究成纤维细胞生长因子18(FGF18)是否能诱导体外分离培养的人牙龈成纤维细胞(HGFs)向成骨样细胞分化,并探究其成骨机制。方法组织块法分离培养HGFs并鉴定。取第3代HGFs,分为实验组和对照组。实验组加入FGF18和L-DMEM、对照组加入L-DMEM。噻唑蓝(MTT)法检测不同浓度FGF18(0、0.01、0.02、0.04、0.06 mg/L)对HGFs增殖影响;碱性磷酸酶(ALP)和茜素红染色检测成骨能力和矿化能力;RT-PCR、免疫细胞化学染色及Western blot检测成骨相关基因、蛋白和BMP信号通路中BMP2基因和蛋白表达情况。结果与对照组比较,实验组培养3、5、7、9、11 d均可促进HGFs增殖(P<0.05);培养14、21 d ALP活性、矿物盐沉积均增高(P<0.05),ALP、OPN、OCN及BMP信号通路中BMP2 mRNA表达均明显增高(P<0.01)。培养21 d OPN、OCN及BMP2蛋白表达较培养14 d明显增高(P<0.01)。结论FGF18能促进HGFs增殖,诱导HGFs向功能性成骨样细胞分化,其成骨机制与上调BMP2有关。展开更多
基金Key-Area Research and Development Program of Guangdong Province(2023B0909020004)Project of Innovation Research Team in Zhongshan(CXTD2023006)+1 种基金Natural Science Foundation of Guangdong Province(2023A1515011573)Zhongshan Social Welfare Science and Technology Research Project(2024B2022)。
文摘Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).
文摘目的研究成纤维细胞生长因子18(FGF18)是否能诱导体外分离培养的人牙龈成纤维细胞(HGFs)向成骨样细胞分化,并探究其成骨机制。方法组织块法分离培养HGFs并鉴定。取第3代HGFs,分为实验组和对照组。实验组加入FGF18和L-DMEM、对照组加入L-DMEM。噻唑蓝(MTT)法检测不同浓度FGF18(0、0.01、0.02、0.04、0.06 mg/L)对HGFs增殖影响;碱性磷酸酶(ALP)和茜素红染色检测成骨能力和矿化能力;RT-PCR、免疫细胞化学染色及Western blot检测成骨相关基因、蛋白和BMP信号通路中BMP2基因和蛋白表达情况。结果与对照组比较,实验组培养3、5、7、9、11 d均可促进HGFs增殖(P<0.05);培养14、21 d ALP活性、矿物盐沉积均增高(P<0.05),ALP、OPN、OCN及BMP信号通路中BMP2 mRNA表达均明显增高(P<0.01)。培养21 d OPN、OCN及BMP2蛋白表达较培养14 d明显增高(P<0.01)。结论FGF18能促进HGFs增殖,诱导HGFs向功能性成骨样细胞分化,其成骨机制与上调BMP2有关。
