JOINT WEBINAR - Ocean Tribology - Nov -25, MoM

Welcome, Introduction and Overview of Ocean Tribology Webinar and Organizing Parties:

Christian von der Ohe and Nuria Espallargas introduced the joint webinar, highlighting its organisation by the CETP MORE Project, the COST Ocean Tribology Centre, and the European Federation of Corrosion Work Party 18, with a focus on R&D collaboration in ocean tribology and multi-degradation across Europe.

• Webinar Structure and Participation: Christian outlined the webinar's structure, including six presentations on ocean tribology, a coffee break, and a Q&A session, with questions to be submitted via the Q&A function and presentations available upon direct request to presenters.

• Organising Bodies and Stakeholders: The event was jointly organised by the CETP Moore Project, the Ocean Tribology Centre (a PAN European Cost Network), and the European Federation of Corrosion Work Party 18, with Christian and Nuria representing all three groups and aiming to promote collaboration and knowledge sharing for sustainable ocean systems.

• Aims and Scope: The webinar aimed to disseminate efforts in promoting R&D collaboration, focusing on the development of sustainable, reliable, and energy-efficient ocean systems, and to continue the knowledge exchange initiated in previous years.

Role of Tribocorrosion and Multi-Degradation in Green Energy Transition:

Nuria delivered a comprehensive presentation on the significance of tribocorrosion and multi-degradation in the context of the green energy transition, discussing global energy trends, the need for robust materials in renewables, and the complexity of degradation phenomena in offshore environments.

• Global Energy Context and Efficiency Challenges: Nuria explained the exponential increase in global energy consumption since the 1950s, the dominance of fossil fuels, and the recent decline in energy intensity improvement rates, emphasising the urgency for clean energy and efficient use.

• Importance of Robust Materials for Renewables: She highlighted the necessity for reliable and robust materials in renewable energy systems, particularly offshore, due to harsh environments involving corrosion, friction, wear, and lubricant interactions, necessitating advanced material testing and qualification.

• Definition and Mechanisms of Tribocorrosion: Nuria clarified that tribocorrosion is not merely the sum of wear and corrosion but a synergistic phenomenon where corrosion significantly accelerates wear, especially in passive metals, and described laboratory methods for measuring these effects.

• Multi-Degradation and Its Testing: She described the transition from tribocorrosion to multi-degradation, where additional mechanical actions such as bending and fatigue further accelerate material loss, and discussed the development of dedicated test rigs and methodologies to study these combined effects.

• Implications for Material Qualification: Nuria concluded that understanding and testing for tribocorrosion and multi-degradation are essential for qualifying materials for next-generation renewable energy systems, with ongoing projects aiming to develop guidelines and tools for industry adoption.

Knowledge Transfer and Survey Findings from Oil and Gas to Renewables:

Christian presented the outcomes of the MORE Project's work package on knowledge transfer, detailing survey results from the oil and gas sector, differences in material qualification approaches, and the need for harmonised guidelines for offshore renewables.

• Survey Methodology and Respondent Profile: A survey was conducted among 56 respondents from the offshore and maritime industry, primarily oil and gas, to assess experiences and needs regarding material qualification for tribological applications.

• Key Survey Findings: Results indicated a strong interest in improved guidelines for multi-degradation material qualification, recognition of downtime from tribocorrosion as a major risk, and a demand for more material and coating options and supplier diversity.

• Differences Between Oil and Gas and Renewables: Christian explained that oil and gas operators often accept current materials and coatings due to higher budgets and custom solutions, whereas renewables require longer service life, standardisation, and cost-effective solutions due to economic constraints.

• Experience Transfer and Service Life Data: The project compiled service life data from oil and gas operations, particularly focusing on piston rod failures in harsh marine conditions, to inform the development of improved qualification guidelines for renewables.

Development and Validation of Multi-Degradation Test Rigs:

• Hamid Khanmohammadi described the design, downsizing, and validation of new small-scale and lab-scale multi-degradation test rigs at NTNU as part of WP3 in the MORE-project, aimed at advancing fundamental research and harmonising testing protocols for materials and coatings under combined degradation scenarios.

• Design and Downsizing Challenges: Hamid outlined the process of downsizing test samples and rigs from previous large-scale designs, addressing challenges such as applying both tensile and compressive stresses and ensuring accurate measurement of friction and wear.

• Prototype Development and Validation: Two groups of bachelor students contributed to the design and prototyping of different test rigs, with iterative improvements made to address measurement accuracy and third-body particle effects, leading to successful dummy and real tests.

• Preliminary Test Results: Initial tests on 316L stainless steel under various bending and tribocorrosion scenarios showed significant increases in volume loss with static and cyclic bending, and post-mortem analyses revealed differences in surface chemistry and recrystallisation.

• Future Testing Plans: Ongoing and planned work includes baseline testing with passive and active metals, potential static multi-degradation tests to separate chemical and mechanical losses, and evaluation of various coatings, including polymer-based solutions, to inform new industry guidelines.

Lubricant Degradation Pathways and Impact on Tribocorrosion:

• Dieter Fauconnier presented an analysis of lubricant degradation mechanisms in ocean energy systems, identifying three main pathways—oxidative ageing, seawater ingress, and harsh operation—that can accelerate tribocorrosion and threaten equipment reliability.

• Ocean Energy System Challenges: Dieter described the main pillars of ocean energy (offshore wind, tidal, wave), the prevalence of tribological elements requiring lubrication, and the increased severity of operating conditions in renewables compared to traditional offshore wind.

• Lubricant Types and Additives: He detailed the composition of lubricants used in gear transmissions, focusing on environmentally acceptable base oils and additive packages designed to protect both the bulk fluid and metal surfaces.

• Degradation Mechanisms: Dieter explained how factors such as oxygen, seawater, heat, shear, contaminants, microbial activity, and electrical discharges interact to degrade lubricants, leading to film breakdown, additive depletion, and increased wear.

• Three Degradation Pathways: He identified oxidative ageing (leading to acid and sludge formation), seawater contamination (causing hydrolysis and microbial degradation), and harsh operation (resulting in thermal cracking, shear, and micro-dieseling) as the main routes to accelerated tribocorrosion.

CO2 Tribocorrosion Mechanisms and Material Selection:

Manel Rodriguez Ripoll discussed the significance of CO2 environments in tribocorrosion, the interplay between wear and corrosion in various industrial sectors, and the need for dedicated testing to select suitable materials and coatings.

• Industrial Relevance of CO2 Environments: Manel highlighted the occurrence of CO2 corrosion in oil and gas, geothermal energy, and carbon capture and storage, noting the rapid degradation of components exposed to simultaneous wear and CO2 corrosion.

• Testing Approaches and Limitations: He described the use of high-pressure, anoxic autoclave systems for corrosion testing and the inadequacy of simplified tribological tests for material selection under realistic CO2 conditions.

• Mechanisms of CO2 Tribocorrosion: Manel explained the formation and protective role of iron carbonate layers, the impact of wear on these layers, and the necessity of simultaneous wear-corrosion experiments to capture real degradation mechanisms.

• Material and Coating Evaluation: He presented findings on the performance of various corrosion-resistant alloys and coatings, showing that microstructure and deposition process, rather than hardness alone, govern durability in CO2 tribocorrosion.

• Corrosion Inhibitor Performance: Manel demonstrated the use of advanced test rigs to evaluate the effectiveness of corrosion inhibitors under wear, showing that increased inhibitor concentration reduces wear scar width and alters surface corrosion patterns.

Failure Analysis of Offshore Wind Turbine Bearings:

Szymon Bernard presented a detailed failure investigation of a generator bearing from a wind farm, revealing subsurface fatigue, misalignment, and evidence of electrical discharge as contributing factors, and emphasised the importance of open sharing of failure cases.

• Case Study Background and Methodology: Szymon described the rare opportunity to analyse a failed generator bearing, detailing the bearing's specifications, operational history, and the process of cleaning, grease analysis, and dimensional checks.

• Findings on Failure Mechanisms: The investigation revealed a spall region in the inner race, subsurface cracks, white edge cracking, and uneven hardness distribution, all indicative of subsurface fatigue exacerbated by misalignment and possible manufacturing inconsistencies.

• Evidence of Electrical Discharge: SEM analysis identified spherical dendritic particles characteristic of electrical discharge, suggesting that despite the use of ceramic balls, discharges occurred between the cage and raceways, contributing to lubricant contamination and wear.

• Implications and Call for Data Sharing: Szymon stressed the difficulty in accessing failure data due to confidentiality agreements and encouraged greater openness in sharing such cases to advance understanding and improve reliability in offshore renewable applications.

Interactive Workshop and Audience Insights:

Christian and Jan Helge Viste facilitated an interactive workshop using Mentimeter, gathering input from participants on their industry backgrounds, application interests, material and lubricant preferences, and degradation challenges, to inform future research and collaboration.

• Participant Demographics and Interests: The audience primarily represented offshore renewables, with interests spanning lubricants, tribocorrosion, gears, bearings, seals, and hydraulic cylinders, reflecting the webinar's relevance to current industry challenges.

• Material and Lubricant Preferences: Participants indicated strong interest in laser claddings, polymeric and elastomeric materials, and water-based or biodegradable lubricants, aligning with the research focus areas discussed during the webinar.

• Degradation and Qualification Priorities: Responses highlighted the complexity of degradation mechanisms, the importance of accurate service life prediction, and the need for comprehensive qualification methods, reinforcing the themes of the technical presentations.

Closing Remarks and Future Collaboration Opportunities:

Christian, Manel, and Nuria concluded the webinar by inviting participants to engage with ongoing projects, upcoming conferences, and collaborative networks, and encouraged continued knowledge sharing to support the advancement of ocean tribology and renewable energy.

• Project and Network Engagement: Participants were encouraged to connect with the More Project, the Ocean Tribology Cost Action, and the European Federation of Corrosion Working Parties, with information provided on ongoing mapping and guideline development activities.

• Upcoming Conferences and Sessions: Manel announced the organisation of a joint session on wear and corrosion in green energies at the next Eurocorr conference in Dublin, inviting attendees to participate and contribute.

• Emphasis on Knowledge Sharing: The organisers reiterated the value of sharing failure cases and research findings to accelerate progress in offshore renewables and tribology, and thanked all presenters and participants for their contributions.