Effect of focused ion beam sample preparation on the phase composition of zirconia

The investigation of phase transformations in metastable ceramic systems such as zirconia often requires local phase analysis within the areas of interest. Electron backscatter diffraction is a suitable method in combination with focused ion beam sample preparation. The interaction between ion beam and sample has to be carefully considered. In case of metastable Y-PSZ and Mg-PSZ, phase transformations were observed after FIB preparation with 30?kV, 30?nA and 5° incidence angle. Damage was the dominating effect for angles of 72°. The expected local temperature increase due to the ion bombardment with 30?kV and 30?nA is 700?K for ZrO₂. Thus, the observed phase transformations can be explained on the basis of the temperature increase in the corresponding Y-PSZ phase diagram. In case of Mg-PSZ, the transition temperature is 1083?°C. The local temperature increase was obviously lower. The excitation energy for the observed phase transformation was smaller than expected from the phase diagrams of the thermodynamic equilibrium. Using 5?kV, 4.8?nA and 5° incidence angle, no phase transformations and no damage were observed. Thus, these conditions are well suited for the FIB preparation of metastable zirconia.     

Dicyanate semi IPNs—A new class of high performance,high temperature plastics

Dicyanate Semi-Interpenetrating Polymer Networks (semi IPNs) are made by dissolving a thermoplastic in crosslinking dicyanates and then curing the resulting mixture. The semi IPNs produced are strong, with tensile strengths of 10,000 to 12,000 psi, and flexible, with elongations to break of 10 to 17 percent. Dicyanate semi IPNs also have good thermal stability and the softening temperatures of the IPNs are significantly, higher than those of the corresponding thermoplastics.     

The determination of molecular weights of polymers from critical concentrations of ternary systems polymer-polymer-solvent

The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation where c_c is the critical concentration, M? the appropriate average of the molecular weight of both polymers; A and c_c∞ are constants for the given system. The possibility of determining the molecular weight of one of the polymers from the value c_c and the molecular weight of the known polymer with the aid of equation (1) is discussed.     

AA4343/AA3003铝合金薄板钎焊接头的显微组织特征

采用气氛保护钎焊工艺 ,对AA434 3/AA30 0 3铝合金复合板材料的钎焊接头组织特征 ,及其与焊接工艺的关系和对接头区显微硬度的影响进行了研究。实验结果表明 ,钎焊过渡区由单相α(Al)固溶体层和Si扩散层组成 ,它们的厚度随钎焊条件而发生变化。远离焊接区有一个α(Al)固溶体残余层 ,它的厚度保持 2 0 μm基本不变 ,与焊接参数和材料性质无关。讨论了钎焊接头特征组织的形成机理     

Information Retrieval and Filtering of Multimedia Mineral Data

Most of the written materials are consisted of Multimedia (MM) information because beside text usually contain image information. The present information retrieval and filtering systems use only text parts of the documents or in best case images represented by keywords or image captions. Why do not use both, text and image features of the documents and in the retrieval or filtering process utilize more completely the document information content? Can such approach increase the effectiveness of retrieval and filtering processes? There is a very little difference between retrieval and filtering at an abstract level. In this paper, we will discuss some possible similarities and differences between them on the application level taking into account the experiments in retrieval and filtering of multimedia mineral information.     

Substitution bias and the construction of a spatial cost of living index*

We estimate the spatial substitution bias based on the difference between a price index (PI) and the true cost of living (COL). This bias is computed at three geographical scales, using several fixed baskets and across different expenditures quartiles. Our results show a significant substitution bias for small geographical units. The choice of the base basket is also relevant for the bias estimation. Finally, the spatial substitution bias is larger for upper side of the expenditure distribution due to the heterogeneity in the consumption basket. This exercise shows that the spatial dimension affects the construction of a price index and that the approach of fixed baskets should be carefully considered in the estimation of spatial price differentials.     

In Situ Characterization of Internal Damage in TRIP‐Steel/Mg‐PSZ Composites under Compressive Stress Using X‐Ray Computed Tomography

An experimental setup for in situ investigations under compressive stress using laboratory X‐ray computed tomography (XCT) was developed and successfully tested. Complete deformation curves can be taken. It could be shown that XCT scans are possible during brakes of the stopped in situ experiments. In this way the deformation behavior of defined sample regions can be investigated. This kind of experiments is well suited to investigate the deformation behavior of foams and other samples which are transferable for the X‐rays used. The compression of metal matrix composite foams lead to the cooperative collapse of connected cells. We observed deformation bands arising in regions of smaller cell wall thicknesses. The deformation was dependent on size, shape, and orientation of the cells under consideration. Obviously deformation bands start at bigger cells with a small cell wall thickness and some extension perpendicular to the deformation direction. The rising of this kind of deformation bands can be explained by the dramatic change of the stress distribution in the neighbor cells after the first brake of a cell wall.     

Characterization of pink diamonds of different origin: Natural (Argyle,non-Argyle), irradiated and annealed,treated with multi-process,coated and synthetic

One of the commercial challenges today in the gem industry is to quickly identify the origin of color in pink diamonds — natural, treated and synthetic by use of standard and advanced gemological instruments.An analytical technique that is used by many gem labs involves UV fluorescence. The principle factors in the technique are the excitation wavelengths and the emission spectra. No systematic study of fluorescence of pink natural diamonds, pink treated and pink synthetic diamonds has been undertaken. This study is mainly focused on using fluorescence techniques to characterize pink diamonds and to compile a reference library of emission spectra. Longwave (LW) and shortwave (SW) fluorescence of 365, 254 and 220 nm illumination were used in a custom built microscope with a fluorescence camera to record images and a spectrometer to record spectral data with which to establish a correlation with the cause of color.Other advanced instruments (CL imaging, UV–VIS–NIR, FTIR, PL spectroscopy and electrical conductance) were used to establish additional criteria for distinguishing natural, treated and synthetic pink diamonds and to find a correlation with the “EGL USA CIS (Cross-reference Identification System) fluorescence method”.     

Degradation von Mikroelektronischen Bondkontakten in ungehäusten Halbleiterbauelementen

Degradation of bondcontacts in chip-on-board microelectronic assemblies The degradation of bondcontacts in Chip-on-Board assemblies under thermic and corrosive stresses were investigated. Degree for quantity of degradation was the changing of the electrical resistance of the bondcontacts. Connections between the silicon die and the substrate (printed circuit board) were manufactured using the well-known ultrasonic bonding process. The PCB's were plated with functional surfaces of Ni and Au by electrolytic or electroless/immersion methods. The deposition method and the thickness of the gold surface have an important influence in the degradation of bondcontacts under thermic and corrosive stresses. The results show that compared to electroless/immersion gold surfaces wire bonds on thick electrolytic deposited gold surfaces (≥ 1.5 μm) tend much faster to degradation.