Papers by Keyword: Corrosion

Abstract: The article analyses corrosive stock in an oil and gas field, and the protection method for the equipment in boreholes and in oil pipelines is discussed. Subsurface pumping equipment corrosion rate monitoring method has been improved. In an oil and gas field, the inhibitor is pumped into the oil pipeline directly into the oil-gathering line and into the production boreholes with different dosages. Pilot testing was carried out to optimize the corrosion inhibitor dosage.

Abstract: The innovative joining process of friction stir welding (FSW) offers a wide range of advantages for welding similar as well as dissimilar materials. Even for the field of poorly weldable material combinations like aluminum to steel with their strongly differing physical properties the method of FSW proved its capability for realizing dissimilar joints with tensile strengths up to more than 80 % of the aluminum base material. Trying to improve this value and other properties of the joints several approaches for hybrid friction stir welding processes were tested in the scientific community, whereas the ultrasound enhancement of FSW (USE-FSW) looked as one of the most promising reaching good results. To gain a deeper knowledge of the influence of the ultrasound on the friction stir welds different investigations were carried out in this paper. Therefore the method of USE-FSW was applied on two dissimilar aluminum/steel-joints with varying carbon content of the steel in this work. The material combinations AA6061/SAE1006 and AA6061/SAE1045 were welded successfully with and without additional power ultrasound. Afterwards a comparison between FSW-and USE-FSW-joints was carried out regarding the microstructure of the nugget and interface (IF) by light-microscopy as well as scanning electron microscopy. Furthermore the mechanical properties were characterized in a first step.

Abstract: While various mechanical properties of SnAgCu (SAC) solder has been reported in the literature the corrosion resistance of solder materials has not been widely reported. This study shows regions adjacent to the Cu₆Sn₅ intermetallic compounds (IMCs) as the corroded region. To investigate the possible formation of a galvanic cell at the interface of SAC solder and the Cu substrate the surface potential distribution at this interface has been evaluated. Results exhibited a comparatively large surface potential difference between SAC solder and the Cu₆Sn₅ IMC indicating SAC solder and Cu₆Sn₅ IMC as the anode and cathode in this system, respectively.

Abstract: Electrochemical migration (ECM) behaviour of Sn-3Ag-0.7Cu and Sn-3Ag-0.7Cu-0.03P-0.005Ni solder alloys were investigated using simulated body fluid (SBF) solution. In electronic devices, ECM phenomenon potentially leads to incompetence or failure of the whole devices. According to water drop test (WDT), mean-time-to-failure (MTTF) of commercially used Sn-3Ag-0.7Cu solder alloy was prolonged with addition of phosphorus (P) and nickel (Ni) as alloying elements. According to microstructure of each solder paste alloy which was observed using field emission scanning electron microscope (FESEM), dendrite structure in Sn-3Ag-0.7Cu-0.03P-0.005 Ni solder was lesser than in plain the Sn-3Ag-0.7Cu. This phenomenon suggested that presence of P and Ni retarded the growth of dendritic thus improved its corrosion resistance. Therefore, Sn-3Ag-0.7Cu-0.03P-0.005Ni possessed a good corrosion resistance in SBF medium.

Abstract: Utilization of Sn-3.0Ag-0.5Cu to replace toxic lead-based solder was only feasible if the corrosion performance of this solder was assured. To obtain this information, potentiodynamic polarization was implement in 3.5 wt. % NaCl. The morphological and structural changes were investigated via crucial characterization methods (SEM and XRD). Collective evidences verified that the needle-like corrosion product confirmed to be made ofSnO, SnO₂ and SnCl^- and responsible to passivation behavior of this solder.

Abstract: Corrosion properties of Sn-9Zn and Sn-0.7Cu solder were investigated in 3.5 wt.% NaCl. The scanning rates used were fixed at 1.0mVs^-1 to study the effect of diffferent adding element which is Cu and Zn into the corrrosion properties of Sn-based solder. The morphological and structural properties of the samples were compared before and after the corrosion. The morphological analysis observed two types of corrosion product which is compacted and loosely-compacted corrosion product after the samples was polarized in 3.5% NaCl solution.

Abstract: The corrosion of Sn-Zn-Bi lead free solder in 6M KOH electrolyte was conducted. The study was done using 3 different KOH concentrations (3M, 6M and 9M) and the immersion technique was used to produce corrosion. Due to the nature of immersion, the solder material was prepared by punching it into small billets size after melting it homogenously on a commercial hotplate. The immersion was set to 7, 14 and 21 days. After the specific days have fulfilled the sample billets were removed and tested. The corrosion of this solder was measured using various method such as graphical analysis, surface roughness, corrosion penetration rate (CPR) and optical microscope. In this research, it was found out that the sample billets taken from 6M concentration compared to 3M and 9M showed more corrosion this was supported by the outcome of the test. The 6M believed to provide best corrosion on the solder billets because of its high ionic conductivity value.

Abstract: The utilization of Sn-Zn based solder on electronic product was only feasible if the corrosion performance of this solder was assured. To achieve this, micro-alloying eutectic Sn-9Zn with Al was proposed. The corrosion performance was evaluated by using potentiodynamic polarization in 1 M HCl at constant scan rate. The microstructure changes due to corrosion exposure was also investigated to further understand the corrosion behaviour changes due to additions of Al. Overall corrosion rate was reduced with the micro-alloying process. Refinement of Zn-rich phase was found to help in producing much lower corrosion current and better passivation film formation on the surface due to the additions of Al. This modification deemed promising and further work should be explored in the future.

Abstract: The paper presents some preliminary results regarding the combining of metallic, Cr3C2-20(Ni 20Cr) and ceramic (TiO₂) HVOF deposition of layers for corrosion protection applications. The deposited layers morphology was investigated by SEM and optical microscopy. The corrosion protection efficiency of the deposited layers was evaluated in 0.3M NaCl solution. The maximum corrosion protection efficiency was determined for the combination of layers using the carbide as the first layer although the inverse deposition order showed a small decrease. Depending on the main application (corrosion versus wear) one or the other are recommended.

Abstract: Samples from high compressibility powders (Ancorsteel 1000B) obtained by pressing at different pressures and sintering at 1150 °C, with (IPASW) and without spring steel wire (Φ = 0.5 mm) reinforcement (IPAS), coated and uncoated with zinc samples were selected for study of corrosion behaviour in salt spray and were subjected to mechanical tests (tensile strenght).