Pure Al coatings were fabricated on Cu substrates via kinetic spraying for double-layered Cu liner. The coatings need to endure the high strain rate severe plastic deformation during explosion, in this study, the process optimization of Al deposition was initiated with a definition of “critical velocity” of Al particle in kinetic spraying on a basis of numerical modeling and computations using ABAQUS finite element codes. The simulation results revealed that the critical velocity of Al particle at room temperature (RT) was 780 m s -1 , and the critical velocity decreased as particle temperature increased. On the basis of simulation results, mechanical properties such as bond strength of the coatings formed under various process conditions were evaluated and compared. These properties were discussed in terms of the processing-structure-property relationships.

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.

Grain size, grain distibution, morphology and microstructure are essential properties of powders for thermal spaying. The present article concerns with the comparison of different methods of particel size measurement. The results indicate, that the grain distribution differs from method to method and there is no correlation factor existing to convert the results of different test methods. So, for exact stipulation of powder grain sizes the method for determination has to be declared. Paper text in German.

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.

Package delaminations are often associated with electrical and package reliability problems in IC devices. Delaminations caused by electrical-over-stress (EOS) and moisture expansion during reflow soldering have shown different delamination patterns. A Scanning Acoustic Microscope (SAM) can be used to detect package delaminations. Understanding these delamination signatures can help us quickly identify the failure cause at an early stage of the failure analysis.