Infinite Focus Research Articles

Wetting Behavior of Sintered Nanocrystalline Powders by Armco Fe and 22CrNiMoV5-3 Steel Grade Using Sessile Drop Wettability Technique

The wettability of sintered nanocrystalline oxide powders (CeO2, TiO2, Y3Al5O12, and ZrO2-yttria stabilized) and Al2O3 basis powder (60–70% purity) (product originated in the secondary aluminium production, composed mainly of nano and micrometric aluminium oxide) by liquid Armco Fe and by 22CrNiMoV5-3 steel grade was studied using sessile drop wettability technique. The powders were pressed and sintered under different pressures, heating rates and holding times. The later grinding and polishing surface treatments were characterized by infinite focus microscope. The wetting experiments were carried out under pure Ar atmosphere. A small piece of Armco Fe and steel grade was melted on sintered nano oxides, heating up to 1600°C with a holding time of 10 minutes for each experiment. The contact angles were measured and chemical analyses were conducted on tested samples to characterize the wetting reactions. It was found that sintered nano TiO2 not only suffered considerable wetting by Armco Fe and 22CrNiMoV5-3 steel in both cases, but also reacted with the substrate to form ilmenite and pseudobrookite. The CeO2 substrate and Armco Fe system also showed good wetting behavior. In general terms, it was concluded that wettability was affected by substrate chemical composition, and surface characteristics by sintering conditions. The preliminary results of this investigation may help to determine the suitability of the nanoparticle to be added in a liquid iron based matrix in order to influence the microstructure evolution improving mechanical properties by a fine distribution in the metallic alloy.

Surface Topographical Characterization of Gold Aluminide Compound for Thermosonic Ball Bonding

Relatively little information is available on the growth patterns of gold aluminide compound in accurate 3D measurement as compared with 2D images of the projected surface. A 3D surface imaging technique by using infinite focus microscope (IFM) was proposed in this study to observe and explain the effects of bonding parameters on growth pattern of gold aluminide compound formed between a 25.48 μm 4N gold wire and an aluminum pad metallization. Two bonding factors, which were varied, were ball bonding force and ultrasonic current while bonding time and temperature were kept constant. The 3D surface measurement provides topographical and color information of the bonded region, which indicates that optimum bonding condition has a significant effect on uniform growth and wide coverage area of gold aluminide compound. Results illustrated by this technique were used as additional information to the results produce by the conventional methods such as cross section optical image and scanning electron microscope (SEM) micrographs, to gain a better understanding on the physical behavior of gold aluminide compound.

Micrographic Technique For Linear-Elastic Fracture Evaluation of Crack Initiation Zone

Post fracture analysis is an important methodology to provide enormous important physical insights to the failure mechanisms of a material. The novelty of micrographic approach or technique for linear-elastic fracture characterization of a metallic solid in particular has adopted material forensic techniques for post fracture evaluation through microscopic measurement of crack initiation zone using the Infinite Focus Microscope (IFM) and the Scanning Electron Microscope (SEM). The IFM has been utilized to analyze the surface roughness profile of the critical fractured surfaces and identify the transition crack initiation zone to develop over a small region of crack increment of about 17 microns. Alternatively, the high magnification SEM could also measure the band width or the incremental crack length at initiation to about 10 microns, in addition to the capability to reveal the microstructures of the crack; namely river patterns and the feather marks, which appear as trademarks leftover due to cleavage linear-elastic fracture. © Asian Network for Scientific Information.

Volumetric analysis of osteoclastic bioresorption of calcium phosphate ceramics with different solubilities

Commonly, to determine osteoclastic resorption of biomaterials only the resorbed area is measured. The depth of the resorption pit, however, may also be important for the performance of a material. To generate such data we used two calcium phosphate ceramics (Ca(10) and Ca(2)). The solubility of the materials was determined according to DIN EN ISO 10993-14. They were scanned three-dimensionally using infinite focus microscopy and subsequently cultivated for 4 weeks in simulated body fluid without (control) or with human osteoclasts. After this cultivation period osteoclasts number was determined and surface changes were evaluated two- and three-dimensionally. Ca(10) and Ca(2) showed solubilities of 11.0+/-0.5 and 23.0+/-2.2 mgg(-1), respectively. Both materials induced a significant increase in osteoclast number. While Ca(10) did not show osteoclastic resorption, Ca(2) showed an increased pit area and pit volume due to osteoclastic action. This was caused by an increased average pit depth and an increased number of pits, while the average area of single pits did not change significantly. The deduced volumetric osteoclastic resorption rate (vORR) of Ca(2) (0.01-0.02 microm(3)microm(-2)day(-1)) was lower than the remodelling speed observed in vivo (0.08 microm(3)microm(-2)day(-1)), which is in line with the observation that implanted resorbable materials remain in the body longer than originally expected. Determination of volumetric indices of osteoclastic resorption might be valuable in obtaining additional information about cellular resorption of bone substitute materials. This may help facilitate the development of novel materials for bone substitution.

Osteoclastic Bioresorption of Biomaterials: Two- and Three-Dimensional Imaging and Quantification

Bioresorbable materials have been developed in the hope that the body will replace them with newly formed tissue. The first step of this remodeling process in bone is the bioresorption of the material by osteoclasts. The aim of this study was to analyze osteoclastic resorption of biomaterials in vitro using the commonly used two-dimensional methods of light-microscopy (LM) and scanning electron microscopy (SEM) in comparison with infinite focus microscopy (IFM), a recently developed imaging method allowing for three-dimensional surface analysis. Human hematopoietic stem cells were cultivated in the presence of the cytokines M-CSF and RANK-L for 4 weeks directly on dentin and a calcium phosphate cement. Osteoclast development was surveyed with standard techniques. After removal of the cells, resorption was characterized and quantified by LM, SEM and IFM. Osteoclast cultures on the biomaterials presented the typical osteoclast-specific markers. On dentin samples LM, SEM as well as IFM allowed for discrimination of resorption. Quantification of the resorbed area showed a linear correlation between the results (LM vs. SEM: r=0.996, p=0.004; SEM vs. IFM: r=0.989, p=0.011; IFM vs. LM: r=0.995). It was not possible to demarcate resorption pits on GB14 using LM or SEM. With IFM, resorption on GB14 could be visualized and quantified two- and three-dimensionally. In this paper we introduce IFM as a technology for three-dimensional visualization and quantification of resorption of biomaterials. Better understanding of the bioresorption of biomaterials may help in the design of better materials and might therefore constitute an important step on the avenue to the development of artificial bone.

Sn-rich phase coarsening during isothermal annealing for as-soldered Sn–Ag–Cu solder

The effect of Sn-rich coarsening in Sn–Ag–Cu solder joints produced by isothermal annealing was investigated. The isothermal annealing temperatures employed were from 30 to 150 °C for 24 h up to 1,008 h of annealing time. An Infinite Focus Measurement system (IFM®) and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) were used for microscopic analysis and elemental analysis, respectively. As the annealing time and temperature increased, a eutectic component Cu, diffused into the Sn-rich phases, coarsening the Sn-rich phases, and the activation energy value for the coarsening was determined to be 41 kJ/mol.

Selection of Electrode Area for Electrochemical Noise Measurements for CO2 Corrosion in Different NaCl Solutions

Electrochemical investigation of localized CO2 corrosion of X-65 mild steel in 0.1, 1.0, 10 and 20 wt% NaCl solutions at 80oC has been conducted using linear polarization resistance (LPR) and electrochemical noise (EN) techniques. EN measurements were carried out only on 11.6 cm2 electrodes in 0.1, 10 and 20 wt % NaCl solution. EN was obtained from both 11.6 cm2 and 1 cm2 electrodes in 1 wt % NaCl solution to learn how the surface area affects EN measurements. Current noise and potential noise between two nominally identical electrodes were simultaneously recorded using a ZRA (Zero Resistance Ammeter). Chemical dissolution of corrosion product layer was accomplished by adjusting pH and saturation values with respect to FeCO3. Surface morphologies and pit depths were observed by scanning electron microscopy (SEM) and infinite focus microscopy (IFM) for 3D optical analysis. The results showed that electrode size influenced the EN signal. Transients related to metastable pitting were best observed with 1 cm2 coupons in 1 wt % NaCl solutions, but such transients were not clearly obtained for 11.6 cm2 coupons in the 0.1, 1, 10, 20 wt % NaCl solution. Both general corrosion rate and localized corrosion rate did not significantly change with increasing NaCl concentrations.

A practical investigation on nickel plated copper heat spreader with different catalytic activation processes for flip-chip ball grid array packages

This study investigates the effects of two different catalytic activation techniques on the thermal performance of the flip-chip heat spreaders. The two activation techniques studied are thin nickel–copper strike and galvanic initiation. Thermal diffusivity and surface roughness of these heat spreaders were studied using the Nano-flash Apparatus and Infinite Focus Microscopy. High temperature storage tests were carried out to investigate the extent of intermetallic diffusion between the nickel and copper layers. The results show that heat spreaders with thin nickel–copper strike catalytic activation technique have a lower thermal diffusivity due to the low thermal conductivity of nickel–copper layer. Moreover, the nickel–copper layers grew thicker from around 0.2 μm at initial time to around 0.55 μm after high temperature storage duration of 168 h. On the other hand, heat spreaders processed using the galvanic initiation technique did not form any nickel–copper intermetallic diffusion layer. As a conclusion, the galvanic initiation technique can potentially provide better thermal performance for heat spreaders used in semiconductor packages.

Comparison of 3D Surface Reconstruction Data from Certified Depth Standards Obtained by SEM and an Infinite Focus Measurement Machine (IFM)

The Scanning Electron Microscope (SEM) is an excellent tool for the characterization of surfaces. In order to evaluate the accuracy of the reconstruction of a 3D dataset, a known depth standard for tactile depth measurement devices with a step height of 92 µm was investigated by SEM. The reconstruction of surfaces using two tilted images (StereoCreator) or three different tilted images (TriCreator) is affected by the tilt angle itself, the image resolution and the working distance. We compare the results of the obtained data from different combinations of tilt angles and working distances in relation with the type of reconstruction…. To compare the accuracy and reliability of the 3D datasets from the new Infinite Focus Measurement Machine (IFM) with the datasets reconstructed from the well known SEM technique, we utilized a groove standard with six trapezoidal grooves with known width and depth certified by the PTB – Braunschweig – Germany (Physikalisch – Technische Bundesanstalt Braunschweig – calibration mark 035PTB04 – measured with a traceable stylus instrument according to DIN EN ISO 3274). The great advantage of the SEM/ESEM (Environmental Scanning Electron Microscope) and IFM technique compared to tactile-profile-measurement instruments is that it is a non-tactile and a non-destructive method. The potential and accuracy of these methods in comparison to tactile measurement systems is shown and discussed in this paper.

Purines and ischemic preconditioning in rat hearts

The aim of the study was to evaluate the effect of resin infiltration on colour changes and surface roughness of artificial white spot lesions (WSLs) on maxillary and mandibular premolar.Sixty (60) extracted sound Maxilla (Mx) and Mandibular (Mn) premolars were randomly divided into 2 groups (test and control). Artificial WSLs were produced on buccal surface of teeth and were immersed in artificial saliva for 8 weeks. Colour components (L∗, a∗, b∗) and surface roughness (Sa∗) were assessed on 40 teeth using colour difference meter RD-100 and Alicona® Infinite Focus profilometer respectively. The measurements were done at baseline (T1), directly after artificial WSLs (T2), after 24 hours immersed in saliva and application of resin (T3) and immersion in artificial saliva for 1 (T4), 2 (T5), 4 (T6), 6 (T7) and 8 (T8) weeks. SEM images analysis were carried out on 20 teeth in four time points.The values of L∗ (lightness), b∗ (yellow/blue) and Sa∗ (surface roughness) are gradually reduced to the baseline value. Whereas, the value of a∗ gradually increased with distinct treatment time to achieve the baseline value. The higher value of L∗ and Sa∗, the whiter the lesion suggesting higher degree of enamel demineralization and surface roughness. Lower L∗ values suggest a masking colour effect.The material produced favorable esthetics on colour and the surface roughness of teeth at distinct treatment times. It is recommended to be used to improve WSL post orthodontic treatment.

Distribution properties of multiply-with-c arry random number generators

We study the multiply-with-carry family of generators proposed by Marsaglia as a generalization of previous add-with-carry families. We define for them an infinite state space and focus our attention on the (finite) subset of recurrent states. This subset will, in turn, split into possibly several subgenerators. We discuss the uniformity of the d d -dimensional distribution of the output of these subgenerators over their full period. In order to improve this uniformity for higher dimensions, we propose a method for finding good parameters in terms of the spectral test. Our results are stated in a general context and are applied to a related complementary multiply-with-carry family of generators.

Month in the Patent Office

In order that the pilot shall not be forced to look downwards to consult his instruments during alighting, especially in the case of an aircraft landing upon an aircraft carrier when the pilot would be obliged to look away from the batsman, an image of an instrument such as an airspeed indicator or stall warning indicator D is projected on to the windscreen E and reflected along the pilot's line of vision FG. In the arrangement shown a beam of light from a lamp A is projected through the translucent dial B of the instrument and through a collimating lens system C so that the image is projected at an infinite focus and the pilot thus avoids having to alter the focal distance of his vision.