Statistical analysis of the removal of aluminum and magnesium impurities from wet-process phosphoric acid

The present paper relates to the treatment of crude wet-process phosphoric acid with ammonium nitrate and hydrofluoric acid to precipitate aluminum and magnesium impurities in the form of an easily separable phase: (NH₄)_xMg_yAl_z (F, OH)₆.2 H₂O. To check the effect of some concentration factors on this reaction, an orthogonal central composite design is realized with three variables: %Al³⁺, %NH₄⁺ and %F^?. It is concluded that the amount of aluminum in acid is the limiting factor of magnesium precipitation. Thus complete removal of magnesium, which is a major impurity in wet-process phosphoric acid, can be obtained by adding to the crude acid extra soluble aluminum salt simultaneously with hydrofluoric acid and ammonium nitrate.     

Development of High Strength Magnesium Based MMC Reinforced with SiC Particles for Satellite Structure Applications

The appearance of Metal Matrix Composites has opened a new area in structural design. The possibility of tailoring mechanical properties of structural metals reinforced with particles or fibers into specific spacecraft applications is very appealing. This paper deals with such a MMC, which is based on a magnesium alloy matrix and SiC reinforcement. The technology used is a commercial semi‐solid die‐casting, which promises a cost‐effective solution. The results of the first stage of this research are discussed with a focus on the satellite structure design application. The next steps of this investigation are also presented.     

Influence of testing parameters on the corrosion rate of magnesium alloys

In sodium chloride solutions alloy composition, phases, microstructure and grain size influence the corrosion behaviour of magnesium alloys. Concentration and distribution of the critical impurities iron, nickel and copper affect the corrosion performance strongly. Salt spray tests according to ASTM B 117 or DIN 50021 are used to control quality of magnesium alloys. Results of these tests often estimate alloy subcontractors and are therefore very important to placing. Standards specify test solution, test temperature and position of specimens during test in the salt spray chamber. Standards not prescribe preparation of test specimens, exposure period, handling of the specimens after salt spray test nor the interpretation of the results. Results of salt spray tests can be only compared, provided that test conditions are exactly given. Whether the standards fulfil the above described criteria, will be shown by extensive investigations. Therefore the influence of exposure period, surface condition and microstructure was investigated.     

氧化镁延迟性膨胀水泥

大体积混凝土常因水泥水化过程的放热而使体内温度升高,在之后的降温阶段混凝土收缩而导致开裂。为了防止这种收缩,研制了延迟性膨胀水泥。其一是生产高镁水泥熟料,其二是在水泥粉磨时掺入煅烧的MgO。试验证明,在适当条件下可制得在7—30天内膨胀的水泥,但这种膨胀在3个月之后即趋于稳定,这就有可能补偿降温引起的收缩,同时又能保证制品的安定性。     

A sample preparation for quantitative determination of magnesium in individual lymphocytes by electron probe X-ray microanalysis

We present a sample preparation method for measuring magnesium in individual whole lymphocytes by electron probe X-ray microanalysis. We use Burkitt's lymphoma cells in culture as the test sample and compare X-ray microanalysis of individual cells with atomic absorption analysis of pooled cell populations. We determine the magnesium peak-to-local continuum X-ray intensity ratio by electron probe X-ray microanalysis and calculate a mean cell magnesium concentration of 39± 19 mmol/kg dry weight from analysis of 100 cells. We determine a mean cell magnesium concentration of 34 ±4 mmol/kg dry weight by atomic absorption analysis of pooled cells in three cell cultures. The mean cell magnesium concentrations determined by the two methods are not significantly different. We find a 10% coefficient of variation for both methods of analysis and a 30% coefficient of variation in magnesium concentration among individual cells by electron probe X-ray microanalysis. We wash cells in ammonium nitrate for microanalysis or in buffered saline glucose for atomic absorption analysis. We find cells washed in either solution have the same cell viability (85%), recovery (75%), cell volume (555 μm³) and cytology. We air dry cells on thin film supports and show by magnesium X-ray mapping that magnesium is within the cells. We conclude that: (a) our microanalysis cell preparation method preserves whole intact lymphocytes; (b) there is no systematic difference in results from the two methods of analysis; (c) electron probe X-ray microanalysis can determine the variation in magnesium concentration among individual cells.     

冶炼铅锌废渣配料对湿法回转窑生产的影响

研究了冶炼铅锌废渣配料对湿法水泥生产的影响。研究结果表明，冶炼铅锌废渣配料，在相同水分情况下，可使生料浆流动度增加2－3mm，生料易烧性较好；冶炼铅锌废渣配料不仅有利于A矿的形成与发育，促进A矿的快速生长，增加A矿含量，提高熟料烧成质量，而且有利于延长烧成带镁铬砖的寿命。     

SiCw／AZ91镁基复合材料的组织及拉伸性能

对高压铸造方法制备的SiCw/AZ91镁基复合材料和AZ91材料的压铸态、挤压态的显徽组织进行了观察分析,并对其拉伸性能进行了测试。结果表明,铸态复合材料中SiC晶须呈混乱分布。而挤压态复合材料中SiC晶须转向挤压方向分布。拉伸试验证明,复合材料的拉伸强度均较基体合金有较大的提高,挤压态的拉伸强度均较铸态有所提高。     

Bidirectional Reflectometry. Part I.: A High Resolution Laser Bidirectional Reflectometer With Results on Several Optical Coatings

A laser-source bidirectional reflectometer that is fully automated and has angular resolution on the order of one degree has been designed and built. The direction of incidence and viewing can be independently varied over an entire hemisphere except for directions more than 77.5° from the normal, and the two directions must be at least 2.5° apart. Bidirectional reflectances for 15 samples of black and white coatings are presented.     

Infrared measurement and simulation of magnesium alloy welding temperature field

The magnesium alloy with the light weight, high specific strength, and recyclable characteristics is praised as the green engineering material in the 21st century[1]. No matter how the alloys are processed either via die casting or a wrought route, such as hot extrusion or press forming, an appropriate bonding technique is needed. It is well known that the welding temperature field determines the stress and strain field during the weld-ing, and it also has the relationship with metallurgy and …     

挤压态SiC_w∥AZ91镁基复合材料的组织及其性能

采用SEM和电子拉伸机对挤压态SiC/AZ91镁基复合材料的显微组织进行了观察分析,并对其拉伸性能进行了测试。结果表明:挤压态复合材料中SIC晶须沿挤压方向分布,SiC晶须的长径比降低;挤压态复合材料的拉伸强度均较压铸态有提高。