Brine-Induced Tribocorrosion Accelerates Wear on Stainless Steel: Implications for Mars Exploration

Tribocorrosion is a degradation phenomenon of material surfaces subjected to the combined action of mechanical loading and corrosion attack caused by the environment. Although corrosive chemical species such as materials like chloride atoms, chlorides, and perchlorates have been detected on the Martian surface, there is a lack of studies of its impact on materials for landed spacecraft and structures that will support surface operations on Mars. Here, we present a series of experiments on the stainless-steel material of the ExoMars 2020 Rosalind Franklin rover wheels. We show how tribocorrosion induced by brines accelerates wear on the materials of the wheels. Our results do not compromise the nominal ExoMars mission but have implications for future long-term surface operations in support of future human exploration or extended robotic missions on Mars.

Optimizing And Comparative of Polymer-45S5BG and Polymer- HA Coating by Electrophoretic Deposition (EPD)

In this study, two systems of bio-ceramic coating (45S5 bioactive glass and hydroxyapatite) were used in order to compare between them for biomedical applications. Each system consists from two layers of coating done by electrophoretic deposition (EPD) technique on 316L stainless steel material as substrate. Two types of biopolymer were used (Chitosan with Gelatin) as first layer of coating. Taguchi approach with L9 array was used in order to choose the best conditions (concentrations, voltage and time) for coating layers. Each system consists of two layer (biopolymer (first layer) and bioceramic (second layer)) materials. The optimum parameters for first layer of biopolymer was (3g/L concentration, 20 voltage and 3 minute) while optimum parameter for second layer (6g/L concentration, 30 voltage and 1 minute) for two bioceramic group. Zeta potential test were employed to measure suspensions stability. The tape test method was used to evaluate the adhesion between substrate and coating layers, the results show that the percentage of removal area for optimum coating layer (biopolymer, 45S5 BG and HA 8.06%, 10.668%, 6.23% subsequently). XRD inspection was used for identify the phases of coating layers. The Cyclic polarization test was used for evaluation of pitting corrosion resistance, the results show all layers gives good corrosion resistance but 45S5BG gives the best corrosion resistance when compared with HA system.

Wear Properties of Stainless Steel Lubricated by Cerbera and Rubber Seeds Methyl Esters under Boundary Lubrication Condition

The use of biodiesel fuel converted from vegetable-based oil are continuously increasing due sustainability and environment concerns. It is important to increase the portion of converted fuel from non-edible sources to reduce the use of food stock. In this study, the tribological properties of stainless-steel material was investigated when lubricated by two kinds of methyl esters converted from non-edible vegetable oils, i.e. Cerbera oil and Rubber seeds oil. The friction and wear were investigated by using a ball-on-disk tribometer at severe friction condition. The results show that the wear of material lubricated by both methyl esters was much smaller than that lubricated by petrol diesel fuel. At temperature of 27°C, the worn area on the ball specimens for the case of Cerbera and Rubber seeds methyl esters were 0.396 mm2 and 0.391 mm2 compared to 3.642 mm2 for the case of petroleum diesel fuel. At 80°C, they were 0.410 mm2 and 0.429 mm2 compared to 4.152 mm2 for the case of petroleum diesel fuel. This shows that both Cerbera and Rubber seeds methyl esters has a good tribological properties comparable to other methyl esters sources used for mineral diesel fuel substitute.

Experimental study on slip resistance performance of ASTM A1010 stainless steel bolted connections

The primary aim of this experimental research was to provide information on the slip coefficient performance of ASTM A1010 stainless steel material and to ascertain if its behaviour is comparable to that of 350W Structural Steel. In accomplishing this task, it was important to examine other parameters associated with slip resistance testing, such as (i) bolt relaxation and (ii) the effect of temperature variation and re-usability of high strength bolts. In the 2014 edition of the Canadian Highway Bridge Design Code, the slip coefficient for clean mill scale and hot dip galvanized surface condition for the 350W structural steel is specified as 0.35, whereas for blasted-clean surface condition is specified as 0.5. Although test results in this research showed lower values for tested structural steel plates, the slip coefficient of A1010 stainless steel material performed better than the 350W structural steel for each surface condition and at the same temperature range. Recommendations regarding the slip resistance test method and the methodology for achieving the required surface conditions in slip resistance connection were drawn.

Experimental study on slip resistance performance of ASTM A1010 stainless steel bolted connections

The primary aim of this experimental research was to provide information on the slip coefficient performance of ASTM A1010 stainless steel material and to ascertain if its behaviour is comparable to that of 350W Structural Steel. In accomplishing this task, it was important to examine other parameters associated with slip resistance testing, such as (i) bolt relaxation and (ii) the effect of temperature variation and re-usability of high strength bolts. In the 2014 edition of the Canadian Highway Bridge Design Code, the slip coefficient for clean mill scale and hot dip galvanized surface condition for the 350W structural steel is specified as 0.35, whereas for blasted-clean surface condition is specified as 0.5. Although test results in this research showed lower values for tested structural steel plates, the slip coefficient of A1010 stainless steel material performed better than the 350W structural steel for each surface condition and at the same temperature range. Recommendations regarding the slip resistance test method and the methodology for achieving the required surface conditions in slip resistance connection were drawn.