Comparison between tribocorrosion behaviour of aluminium bronze and leaded tin bronze in simulated sea water

This paper summarises the main findings of the presentation given in NordTrib2018 conference held in Uppsala, Sweden, on 18-21 June 2018. The presentation concentrated on the comparison of the overall tribocorrosion behaviour of aluminium bronze and leaded tin bronze, the original pieces of research of which have been reported elsewhere. Here, the main results are presented and evaluated

A closer look at the corrosion of steel liner embedded in concrete

Containment wall of nuclear power plants is an example of a concrete structure enveloping a steel liner plate. In this research, the situations observed in connection with liner failures were investigated, namely the presence of a piece of wood (foreign matter) and a delamination gap between steel liner and concrete, with the purpose to study and define the corrosion mechanism of the steel liner plate and identify which factors promote or impede the occurrence of corrosion.Specimens were concrete slabs containing a steel plate, an inlay to modify the conditions at the steel surface, and electrodes for electrochemical measurements. The inlays represented “normal” concrete, low-pH concrete, a piece of wood, and a delamination gap between concrete and steel, and the same systems supplemented with chlorides. The results from two-year tests with wetting-drying cycles revealed localized corrosion in steel underneath the piece of wood, close to the inlay perimeter. The attack could be explained mainly by the mechanism of crevice corrosion. In contrast, no corrosion attack of steel liner could be detected in specimens with the delamination gap. The results from the experiments and steel liner characterization are provided in this paper, together with the reasoning behind the proposed degradation mechanism

Sensor development for corrosion monitoring of stainless steels in H₂SO₄ solutions

Equipment made of different stainless steels is often used in the hydrometallurgical processing industry. In this study, an electrical resistance sensor was developed for monitoring corrosion in acidic solutions at high temperature. Two types of stainless steel were used as the electrode materials, namely grade 316L stainless steel (EN 1.4404) and grade 2507 duplex stainless steel (EN 1.4410). The materials and sensors were exposed to a 10% H2SO4 solution containing 5000 mg/L of NaCl at various temperatures. Results from the sensors were verified using electrochemical techniques and postexposure examination. Results showed that the microstructure played an important role in the interpretation of corrosion rates, highlighting the importance of using an appropriate stainless steel for the production of sensors. Electrochemical tests and postexposure examination both showed that the grade 2507 had a significantly lower corrosion rate compared to the grade 316L. Under industrial‑process conditions, the results for the grade 2507 sensor were promising with respect to sensor durability and performance, despite the extremely harsh operating environment

К 75 -ЛЕТИЮ ВАЛЕРИЯ ИВАНОВИЧА ЧИССОВА

The 75th birth anniversary of Valeriy I. Chissov.К 75 -летию ВАЛЕРИЯ ИВАНОВИЧА Чиссова лауреата Государственных премий РФ и пемии Правительства РФ, заслуженного деятеля науки РФ, заслуженного врача России, академика РАН, доктора медицинских наук, профессора

PENGGUNAAN HIDROLISAT JERAMI PADI (Oryza sativa Linn) SEBAGAI BAHAN DASAR PRODUKSI BIOPLASTIK POLI(3-HIDROKSIBUTIRAT) DENGAN MENGGUNAKAN BAKTERI Bacillus cereus

Jerami padi merupakan limbah biomasssa berselulosa yang berlimpah, dan belum banyak dimanfaatkan. Pada penelitian ini, jerami padi digunakan sebagai sumber karbon dalam fermentasi bakteri untuk produksi biopolimer poli(3-hidroksibutirat), P(3HB). Jerami padi diubah menjadi bentuk hidrolisat menggunakan enzim selulase yang diproduksi oleh fungi Trichoderma viride. Hidrolisat dengan konsentrasi 20, 40, 60, 80 % difermentasi menggunakan inokulum bakteri Bacillus cereus dengan konsentrasi 1, 5, dan 10 %. Kandungan P(3HB) dalam biomassa ditentukan dengan kromatografi gas. Hasil menunjukkan biomassa tertinggi yaitu sebesar 84 mg/100mL pada konsentrasi hidrolisat jerami padi 80% dan inokulum 10%. Kandungan P(3HB) tertinggi dihasilkan sebesar 75,8% pada konsentrasi hidrolisat jerami padi 60% dan inokulum 10%. Kata kunci: jerami padi, fermentasi, poli(3-hidroksibutirat

Penetration of corrosive species into copper exposed to simulated O2-free groundwater by time-of-flight secondary ion mass spectrometry (ToF-SIMS)

ToF-SIMS analysis of copper samples after exposures to simulated groundwater with and without sulfide addition was performed to investigate the penetration of corrosive species containing H, S, O, and Cl, into copper. Depth profiles show extent of penetration and 2D/3D images reveal local elemental distribution of the corrosive species at different depths inside copper. Pre-oxidation did not reduce the penetration while sulfide additional in groundwater and exposure at 60 \ub0C significantly promoted the penetration. The extent of penetration of the corrosive species into copper demonstrates the need for risk assessment of complex corrosion forms such as sulfide-induced embrittlement and cracking

Mining tailings as a raw material for glass-bonded thermally sprayed ceramic coatings : Microstructure and properties

Magnesium aluminate, MgAl2O4, spinel powders for thermal spraying, were synthesized from secondary raw materials by spray drying and subsequent reaction sintering. Talc ore mining tailings and aluminium hydroxide precipitate from aluminium anodizing process were studied. A stoichiometric MgAl2O4 spinel coating was prepared as a reference using pure raw materials. Atmospheric plasma spraying resulted in the formation of ceramic coatings. Microstructural investigations revealed that the reference coatings exhibited crystalline lamellar microstructure of MgAl2O4 but secondary coatings contained amorphous areas between the crystalline MgAl2O4 clusters. Abrasive wear test results revealed considerably lower wear rate for secondary coatings. It is suggested that the different structure of coatings, particularly the high degree of amorphous phase between the isolated crystalline MgAl2O4 clusters caused the higher abrasive wear resistance by changing the wear mechanism. The dielectric breakdown strength of the secondary coatings were at the same level, 24 V/μm, as compared to reference coating, 23 V/μm.acceptedVersionPeer reviewe

Foreword No 3 (2017)

The year’s 2017 end is at hand, meaning it’s time to summarize the highlights of the year. Towards the end of the year, we tribologists had two great reasons to celebrate. On 31st August 2017, The Finnish Society for Tribology reached the cornerstone of 40 years. The 40th anniversary was commemorated through an international seminar, after which the festivities continued with celebratory dinner and speeches. The day offered many interesting presentations, discussions and possibilities for networking. The readers of Finnish Journal of Tribology are provided with an overview of the 40th Anniversary seminar. Just before the Christmas, professor Kenneth Holmberg from VTT Technical Research Centre of Finland Ltd received the highest international award in the tribology field, The Tribology Gold Medal Award. Finnish Journal of Tribology wants to congratulate Kenneth for this great achievement! This end-of-year issue therefore reviews the award declaration for the readers. I hope the New Year will be as prosperous for the tribologists as the ending one.Elina Huttunen-SaarivirtaEditor-in-Chief of Finnish Journal of Tribolog