球磨仪塑料管法用于土壤有机碳测定可行性探讨

土壤有机碳是评估土壤质量的重要指标,土壤有机碳测定通常采用研钵法研磨土样,操作费时费力,不适用于批量样品的测定。球磨仪以高效快捷的优势广泛应用于样品研磨处理,为了探究球磨仪用于土壤有机碳测定的可行性,以研钵研磨法为对照(CK),球磨仪分别使用聚四氟乙烯塑料管A,聚丙烯塑料管B、C、D研磨土壤样品,比较土壤有机碳含量测定的差异。结果表明,球磨仪直接使用塑料管研磨土样,土壤有机碳测定值均大于CK,A管差异最小;水、酒精和丙酮清洗塑料管不能消除对土壤有机碳测定值的影响;球磨仪使用A管研磨,研磨时间对测定值没有明显影响。因此,在土壤有机碳测定实验教学中可以采用聚四氟乙烯塑料管研磨法。

球磨仪制样-微波消解-GFAAS法测定土壤中铅

建立了行星式球磨仪制样-微波消解-石墨炉原子吸收光谱法测定土壤中铅的方法。标准曲线在0～10.0μg/L范围内线性良好,以称样0.5 g、定容体积50ml计,方法检出限为0.10mg/kg,土壤样品测定的RSD<4%,加标回收率为91.4%～102%。

球磨仪-微波消解石墨炉原子吸收法测定土壤中的铅元素

采用行星式球磨仪制样、微波消解、石墨炉原子吸收法测定了土壤样品中的铅含量,球磨仪制样颗粒超细且均匀,干净卫生,不存在扬尘污染;微波消解仪操作简便快速,消耗试剂少,密闭消解,酸污染少。结果表明:测定土壤标准样品GSS-22的相对误差为1%,GSS-26相对误差为1.2%,测定实际试样相对标准偏差均值为1.6%,均满足试验要求。

扫描电镜和球磨仪在硬质合金涂层分析中的应用

采用扫描电镜和球磨仪相结合的方法,可以高效、准确、全面地检测硬质合金数控刀片涂层的性能。结果表明:利用扫描电镜可以观测涂层表面和断面的形貌,利用能谱仪可以半定量涂层成分,采用球磨仪可以快速准确地检测涂层的厚度及定性分析涂层的结合强度。实验结果对硬质合金涂层机理研究、工艺研发和质量控制等具有很好的指导作用。

两种粉碎机型式对鹰嘴豆芽超微粉食用品质的影响

目的 探讨粉碎机型式对鹰嘴豆芽超微粉食用品质的影响。方法 利用碾轧式超微粉碎机和行星式球磨仪对鹰嘴豆芽进行超微粉碎,检测鹰嘴豆芽超微粉的营养成分含量以及物理性质,探究功能成分及抗氧化活性的变化。结果 处理后的行星式球磨粉和碾轧式超微粉两种粉体平均粒径减至常规粉体的10.19%、8.53%;与碾轧式超微粉相比,行星式球磨粉的持水力、水溶性和溶胀力分别是其1.49、1.50和1.43倍,休止角显著增加(P<0.05)、滑角显著降低(P<0.05),L^(*)升高和a^(*)、b^(*)降低更明显(P<0.05);行星式球磨粉获得多于碾轧式超微粉10.30%、15.61%的酚类物质。碾轧式超微粉营养成分含量较多(脂肪6.17 g/100 g、还原糖3.82 g/100 g),具有较强的抗氧化活性。结论 两种粉碎机对鹰嘴豆芽粉具有不同的影响,行星式球磨仪促进酚类物质含量上升更显著,碾轧式超微粉碎机更好地保留粉体流动性和营养功能性。

Nondestructive evaluation of mechanical properties of nanostructured Al-Cu alloy at room and elevated temperatures

The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)test were used for evaluating the mechanical properties of this alloy.The tests were conducted at 21℃ on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios(BPR)of 30:1 and 90:1.Furthermore,the tests were conducted at 200 and 400℃ on the samples that were processed at BPR of 90:1.Increasing BPR resulted in raising the final indentation load from(316±26)to(631±9)N and reducing the final indentation depth from 111 to 103μm.Regarding the samples that were processed at BPR of 90:1,increasing the test temperature from 21 to 400℃ resulted in decreasing the final load from(631±9)to(125±1)N and increasing the final depth from 103 to(116±1)μm.The sample processed at BPR of 90:1 and tested at 21℃ revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400℃ exhibited the lowest strength and the greatest deformability,as compared to all samples under study.

Structural macrokinetics of synthesizing ZnFe_2O_4 by mechanical ball milling

Powder mixtures of Fe2O3 and ZnO were milled in a high-energy planetary ball mill to synthesize ZnFe2O4 and X-ray powder diffractometry was used to obtain the relative content of phases,crystallite size and microstrain of both Fe2O3 and ZnFe2O4. The lattice constants of Fe2O3 were obtained by cell refinement method.The macrokinetics and the structure evolution of matters were studied and the results show that the dynamics process of mechanochemical synthesis of ZnFe2O4 fits Avrami-Erofe’ev model and is controlled by a nucleation-growth mechanism,and the structural macrokinetics theory in combustion synthesis research area could be used to describe the kinetic process as well.

聚四氟乙烯塑料管研磨法对测定C4植物碳同位素比值的影响

聚四氟乙烯(PTFE)塑料管研磨法是测定植物碳同位素比率(δ^(13)C)值常用的前处理方法。该方法处理样品高效快捷,但对植物δ^(13)C可能存在污染。本研究利用人工气候室开展双因素交互试验,包括空气相对湿度(50%和80%)和空气δ^(13)C(^(13)C富集和贫化的空气)两个因素,对比了PTFE塑料管研磨法和不锈钢管研磨法处理C4植物糙隐子草δ^(13)C的结果。结果表明:在相同湿度条件下,不同空气δ^(13)C处理的植物^(13)C分馏值(Δ^(13)C,矫正了光合作用底物的δ^(13)C差异)原本可以视为重复,但由于PTFE塑料颗粒的混入,相同湿度不同^(13)C丰度空气培养下植物叶片Δ^(13)C平均差值为4.8‰。该污染效应导致单个叶片δ^(13)C测定的误差高达8‰。考虑到C4植物的Δ^(13)C较低(通常为1‰~8‰),这种污染效应已经超出了可以接受的误差范围。通过建立类似Keeling曲线的二元混合模型对误差进行了有效消除,并准确估算了植物样品和污染物的δ^(13)C。说明广泛采用的PTFE管研磨方法对研究C4植物Δ^(13)C并不适用,将导致较大的误差。对精度要求较高的研究内容建议使用不锈钢瓶进行研磨。