Super 304H is a new generation of advanced austenitic stainless steels that is increasingly being used in superheater/ reheater (SH/RH) sections of thermal ultra-supercritical steam power plants due to its high creep strength combined with good oxidation resistance and microstructure stability. However, recent studies have shown significant microstructural changes and associated degradation in creep performance during long-term service exposure in this alloy. Microstructure evolution during service and its effect on the long-term creep performance has not been comprehensively assessed. In this work, variations in the microstructure of long-term service exposed Super 304H RH tubes (~99,600 hours at 596°C steam temperature) are documented. The results for the ex-service material are compared to well-documented laboratory studies to provide perspective on improved life management practices for this mainstay advanced stainless steel.

In the semiconductor chip manufacturing industry, a method of evaluating characteristics by applying a direct circuit edit at an already manufactured chip level is widely used in order to shorten the product development time and release the product to the market in a short time. [1] This is because, when the fab process is performed by modifying the mask to improve the characteristics as in the conventional method, it takes a lot of time and cost for feedback. Feedback of semiconductor characteristics through circuit edit can save 10-20 times in terms of cost and time. As the process becomes more complex and the pattern size becomes smaller, its benefits become even greater. However, when the chip level circuit edit is applied to the Chip Scale Package (CSP) IC, it is very difficult to apply a general method of the frontside circuit edit, so that the success rate of the circuit edit is lowered. In order to solve this problem, a circuit edit method in the backside direction of the chip has been attempted for many years. [2, 3] However, the backside circuit edit (BCE) has more difficulties than the frontside circuit edit. A typical issue is how to uniformly and precisely control and remove the backside Si of the circuit edit area. The following three points should be considered for this. First, the uniformity of the remaining silicon thickness should be high. Second, it is necessary to control the thickness of remaining silicon to an appropriate thickness in the process of removing backside silicon. Third, it is important not to damage the peripheral circuit during etching and deposition. In this paper, we propose a method to increase the backside circuit edit success rate of CSP IC using Al or Cu metal by controlling these three factors effectively.

In automotive industry, thermal spray process is used to reduce engine weight by replacing cast iron liners inserted in cylinder bores. Especially, twin wire arc spray is one of widely used thermal spray processes with inexpensive cost and high deposition rate. In this study, two kinds of wire materials, low carbon steel (0.07 wt.%C) and high carbon steel (0.80 wt.%C) were deposited by twin wire arc spray process using two kinds of process gas (i.e., compressed air and nitrogen) in order to elucidate effects of carbon contents of ferrous coating and process gas type on the hardness and wear resistance of coating. In case of hardness, low carbon steel coatings had higher hardness when air was used as process gas whereas high carbon steel coatings had higher hardness when nitrogen was used, which was caused by the counter effects of carbon loss and oxide formation. The results of sliding wear test in lubricated condition indicated that coatings with higher hardness have better wear resistance and oxides improve wear resistance by playing a role as solid lubricant. The main wear mechanism was splat delamination induced by inter-splat crack, and traces of other wear behaviours such as splat tip fracture and abrasive wear were also observed.

In this study, arrested reactive milling (ARM) is used to prepare Al-Ni composite powder for deposition on copper liners via kinetic spraying. Among the main goals are to obtain a better understanding of how the milling process affects deposition efficiency and the reactivity of the coatings and to find a way to reduce the amount of remaining solid lubricant after milling. Al-Ni powders were produced under a wide range of conditions and heated to various temperatures to eliminate stearic acid. The powders were sprayed using fixed process parameters and deposition efficiencies, reactivities, and heat values were measured and are compared along with coating microstructures. The procedures used are described and the findings of the study are presented and discussed.

Mechanically mixed Al-Ni powders with different nickel fractions were deposited on Cu substrates by kinetic spraying. Deposition efficiency and porosity were measured and finite element analysis was used to model single and multiple particle impacts. Increasing the fraction of nickel in the feedstock powder reduced the porosity of the Al-Ni coatings but at the expense of deposition efficiency. The reason for this is explained based on particle velocity measurements and impact models. With that information, dense, well adhered coatings were produced by increasing the tamping effect of Ni, resulting in local melting of the Al at the Al-Ni interface.

Cu 54 Zr 22 Ti 18 Ni 6 amorphous powders were deposited onto aluminum substrates by cold spray process with different powder preheating temperature (below T g : 623K, near T g : 703K, and T x : 773K). The microstructure and macroscopic properties of coating layers were investigated using OM, XRD, DSC and hardness, SUGA test, potentio-dynamic corrosion test. XRD results showed that cold sprayed Cu based amorphous coating layers of 300~350 μm thickness could be well manufactured regardless of powder preheating temperature. Porosity measurements revealed that the coating layers of 623K and 773K preheating temperature conditions had lower porosity contents (0.88%, 0.93%) than that of 623K preheating conditions (4.87%). Hardness was measured as 374.8HV (623K), 436.3HV (703K) and 455.4HV (773K) for the coating layers, respectively. Results from the wear resistance examination via SUGA test and those from the hardness testing showed the same trends. Examination of corrosion resistance of the amorphous coating layer showed that the critical anodic current density (ic) of the coating layer, for which powder preheating was provided at 623K and then cold spray deposition, was 5.6X10-3A/cm 2 . The ic values of the 703K and 773K coating layers were 4.8X10 -4 and 1.2X10 -3 A/cm 2 , respectively. Both temperature conditions were found to offer superior corrosion characteristics to those of the 623K-prehaeted and coated specimen. This was assumed to be attributed to the relatively lower level of porosity.

This study assesses the potential of kinetic-spray coatings for dealing with the effects of soldering and erosion on aluminum casting dies. In the experiments, molybdenum-boride cermet and cobalt-based alloy powders are cold sprayed onto SKD61 substrates. Coating microstructure is assessed via SEM and XRD analysis and several mechanical properties are measured. In order to evaluate soldering resistance, the coatings are immersed in a molten aluminum bath. Although cold-sprayed CoCrNiWC exhibited high coating density and low porosity, its soldering resistance was significantly lower than that of MoB-NiCr. The boride cermet coating not only exhibited superior soldering resistance, but also higher hardness, bond strength, and wear resistance. However, its deposition efficiency needs further improvement.

In this work, effect of substrate roughness on the deposition behavior of the particles through kinetic spray technology is studied. Finite element analysis program, ABAQUS 6.7-2 was used to estimate the results. Particle impact on the planar and roughened substrates were analyzed and compared. Interface temperature, contact area and contact time were found to be higher for the particle impact on roughened surfaces than that of the planar one for constant spray condition. These factors are significant for bonding mechanism. Experiments were performed on the polished and grit blasted surfaces in order to compare the results. The deposition efficiency and the bond strength values were used to evaluate the effect of surface roughness.

As DRAM technology extends into 12-inch diameter wafer processing, plasma-induced wafer charging is a serious problem in DRAM volume manufacture. There are currently no comprehensive reports on the potential impact of plasma damage on high density DRAM reliability. In this paper, the possible effects of floating potential at the source/drain junction of cell transistor during high-field charge injection are reported, and regarded as high-priority issues to further understand charging damage during the metal pad etching. The degradation of block edge dynamic retention time during high temperature stress, not consistent with typical reliability degradation model, is analyzed. Additionally, in order to meet the satisfactory reliability level in volume manufacture of high density DRAM technology, the paper provides the guidelines with respect to plasma damage. Unlike conventional model as gate antenna effect, the cell junction damage by the exposure of dummy BL pad to plasma, was revealed as root cause.

Based on the previous studies of nanostructured WC based coatings, various improvement methods of the coatings were attempted. On of the method was to improve the feedstock materials via a partial flocculation method. This method uses a special technology to form spherical spray dried powders using nanostructured starting materials. According to this method, morphology and porosity level of the feedstock material was controlled. In addition, the basic principle of this method will be introduced. A few other methods are tried to improve the feedstock materials including carbon addition and a Co coating method. The coating morphology and characteristics are analyzed and wear performance is compared. The carbon contents, porosity, phases, and wear loss by a sand abrasion test will be presented in details. Abstract only; no full-text paper available.

The wear characteristics of plasma spray coated layer of Alumina-Titaina composite powder have been investigated, in this study, focusing on the effect of particle size of Alumina powder and parameters of plasma spray coating process. Alumina-Titania composite powders were artificially agglomerated into the size suitable for plasma spray coating process. The process condition for plasma spray coating has been optimized through a statistical data treatment method i.e. response surface analysis. Mechanical properties of coated layer have been measured as a function of the initial Alumina particle size. The structure of Alumina nano-powders in the coated layer was found to be affected by flow rates of Ar and H 2 gases, and the power of plasma in a combinational way. The relationship between the wear characteristics of coated layer and process parameters and microstructure of the coated layer was elucidated, by measuring the size distribution, temperature, and velocity of traveling Alumina-Titania composite powder agglomerates. Abstract only; no full-text paper available.

This paper reports on a study that investigated how low cycle fatigue (LCF) and fatigue crack propagation (FCG) properties of P92, P122, and P23 steels vary between 600°C and 700°C depending on the location relative to a cross weld. Microstructure analysis was also performed on fractured specimens. Due to its higher yield strength, P122 exhibited the best continuous LCF life. However, creep-fatigue interaction (CFI) in the weld heat-affected zone (HAZ) of P122 and P23 steels significantly reduced their lifespans compared to continuous LCF tests. This reduction is attributed to the effect of weld thermal cycles on fine precipitates. FCG tests revealed that the base metal consistently outperformed the HAZ in all tested steels and temperatures. P92 and P122 showed similar FCG rates except for P92's behavior at 600°C, which resembled P23. In both steels, the HAZ exhibited faster FCG rates at 600°C and 700°C compared to the base metal, particularly at lower stress intensity factor ranges (ΔK). Within the HAZ, the region 1 mm from the fusion line displayed the slowest FCG rates, followed by the base metal, while the fusion line and the region 2 mm from it showed the fastest. Fracture surfaces near the fusion line displayed cleavage-like features, while the region 1 mm away exhibited features associated with higher crack growth resistance.

The aim of this study is to find a coating that can improve the wear resistance of bushings and sleeves used in continuous hot-dip galvanizing facilities. In the experiments, a number of wear-resistant alloys and their carbide composites are applied to stainless steel substrates by plasma transferred arc (PTA) surfacing and the resulting deposits are characterized based on XRD and SEM analysis, microhardness measurements, and pin-on-disk sliding wear tests conducted in a molten Zn-Al bath at 470 °C. Changes in microstructure during solidification are discussed and correlations are made with phase composition, hardness, wear behavior, and suspected wear mechanisms. Paper includes a German-language abstract.

Thick thermal spray coatings are used to repair worn parts during aircraft overhaul. The thermal spray coating is used to restore a part to its original dimensions. Characteristics of the as-applied coating that affect the performance of thermal sprayed parts are the residual stress in the coating, the tensile bond strength, the amount of porosity, oxides and impurities near the coating/substrate interface, and the hardness of the coating. An understanding of the relation of these coating characteristics to process variables such as the material used for the coating, spray process, spray angle, and thickness of the applied material is needed. In this paper, four thermal spray coatings, Ni5Al, Ni5Al-atomized, (NiCr)6Al, and Inco 718, on a substrate of Hastelloy X are investigated. These materials are applied using two different thermal spray application processes: plasma spray and High Velocity Oxy-Fuel (HVOF). Spray angles of 90° and 45° are used during spraying. The nominal thickness of the applied coatings ranges from 0.4 mm to 1.8 mm. The thermal spray coatings are evaluated in four types of tests. Residual stresses in the coatings and substrate are evaluated using the modified layer removal method. A tensile bond strength test is performed. Metallographic examination is used to determine the porosity and content of oxides and bond zone impurities (percent) of the applied materials. In addition, the hardness of the coating is measured. For the materials and conditions investigated, it is found that residual stress varies with each of the four process parameters. The bond strength for plasma sprayed coatings is related to the type of material and possibly to the coating thickness. The percent porosity varies with coating material, but, for Ni5Al, it does not depend on application process. Oxide content, as a percentage, varies with material and process, but not with spray angle and thickness. The percentage of impurities near the coating/substrate interface varies with process and, for the specimens that were coated using the HVOF process, with thickness. The hardness of the coating was found to vary with material and spray process. For three of the four coatings, hardness increases with thickness but, for Inco 718, hardness decreases as thickness increases.

One candidate alternative to chrome plating and hard anodizing is a tungsten carbide (WC) coating applied by the High Velocity Oxy-Fuel (HVOF) process. HVOF WC coatings are currently being evaluated in many service life tests, including fatigue. The purpose of this paper is to compare the fatigue life of HVOF WC coated specimens with the fatigue life of hard anodized and bare aluminum specimens. This work examines WC thermal spray coatings as candidates for replacement of hard chrome plating and hard anodizing in aircraft and helicopter applications such as landing gear. In fatigue testing, the results showed an expected fatigue deficit for hard anodizing as compared to bare aluminum. Paper includes a German-language abstract.

Commercially available coating techniques such as "open arc" and "spray & fuse" methods were used to compare the microstructural development with the plasma transferred arc (PTA) coating process for the hardfacing of NiCrBSi and Stellite 6 alloys. Denser eutectic structure was observed in the case of PTA coated layers of the Stellite 6 alloys than those of open arc weld-surfacing process. The shape of both carbides and borides in the 16C alloy coated by PTA processing were also obtained to have coarse morphology of carbides and borides while the "spray & fused" layers show a needle shape with finer distributions. Possible thermal history during each coating process is discussed. Based on microstructural observation, the hardness, wear resistance, and corrosion behaviors are reported. As expected, the alloy properties are directly related to their constituents of microstructure.

Several plasma-sprayed ceramic coatings with two- and three-layers were characterized and tested for the application of cooling tube coatings at the steel making factory. Thermal cycling tests using a torch heating with compressed air cooling were carried out and characterized before and after the tests. The effects of bond coat as well as top coat were also studied. Possible failure mechanisms with low carbon steel substrate were assessed in term of microstructure, porosity, bond strength, thermal expansion coefficient, and the phase transformation. Finally, the results of field tests at the oxygen convert gas recovery system are also discussed.

The thermal expansion characteristics of plasma-sprayed coatings were investigated. The thermal expansion measurements were carried out up to 1200°C on thick coatings that were substrate free. The effects on the thermal expansion coefficients were studied in terms of composition, powder size, porosity, and the phase transformation. The relationships between the thermal shock resistance and the thermal expansion properties of the coatings are also discussed.