Impact Of Corrosion Research Articles

Effect Of Heat Treatment On The Corrosion Resistance Of Aluminized Steel Strips

AbstractThe paper presents the results of corrosion resistance of heat treated aluminized steel strips. Products coated by Al-10Si alloy are used among others in a manufacturing process of welded pipes as the elements of the car exhaust systems, working in high temperatures and different environments (eg. wet, salty). The strips and tubes high performance requirements are applied to stability, thickness and roughness of Al-Si coating, adhesion and corrosion resistance. Tubes working in elements of exhaust systems in a wide range of temperatures are exposed to the effects of many aggressive factors, such as salty snow mud. It was therefore decided to carry out research on the impact of corrosion on the environmental influence on heat treated aluminized steel strips. The heat treatment was carried out temperatures in the range 250-700°C for 30, 180, 1440 minutes. Then the coatings was subjected to cyclic impact of snow mud. Total duration of treatment was 12 months and it was divided into three stages of four months and at the end of each stage was made the assessment of factor of corrosion. The results are presented in the form of macroscopic, microscopic (using a scanning electron microscope) observations and the degree and type of rusty coating.

Bond behaviour of reinforcing bars in cracked concrete

Due to the relatively low tensile strength of concrete, cracks are inherent in reinforced concrete structures. A common cause of cracking is the corrosion of internal steel reinforcement, a deterioration process that can affect the bond behaviour and anchorage capacity of reinforcing bars. Corrosion leads to a reduction of the reinforcing bar diameter, the formation of a weak layer of corrosion products around the bar and expansive forces on the surrounding concrete (that can lead to cracking). In the past, the impact of corrosion on bond has been investigated by means of accelerated corrosion tests. However, the more fundamental impact of cracking as distinct from corrosion products on the bond reduction is still not fully understood.This study applies a novel test method to investigate the bond behaviour of reinforcing bars in cylindrical cracked reinforced concrete specimens. The influence of the number of cracks, crack orientation, confinement and concrete cover are investigated.The results indicate a significant loss of bond strength for single cracked specimens. This reduction becomes as high as 65% for double cracked specimens in the absence of confinement. It is shown that the crack orientation with respect to the rib pattern is of minor influence, but the concrete cover and confinement play a significant role in the obtained bond characteristics.

Pipelines Reliability Analysis Under Corrosion Effect and Residual Stress

This work focuses on a development of a finite element model that simulates corrosion phenomenon and its influence on structure rupture (pipelines). Subsequently, the pitting effect on reliability and pipelines lifetime is studied. In this paper, the investigated structure material is characterized experimentally, in order to determine the maximum strength and stress resistance. Therefore, a numerical model was developed under ANSYS code to simulate different loads to obtain the stress concentration factor as the stresses could surpass the yielding limit in the corrosion impact, and to determine the Von Mises stress. A corrosion model and residual stresses used in the literature are coupled with the probabilistic model to find the limit state function. Thus, failure probability and structure reliability index under the effect of pitting corrosion phenomena are calculated and the obtained results are discussed and analyzed.

Use of natural gums as green corrosion inhibitors: an overview

Corrosion of metals and its alloys employed in service is an inescapable but a controllable process. One of the practical methods for controlling the impact of corrosion of metals and alloys especially in aqueous environments is by using corrosion inhibitors which are composed mainly of organic or inorganic substances. However, the toxicity of organic and inorganic corrosion inhibitors to the environment and humans has compelled the search for safer corrosion inhibitors called ‘green corrosion’ inhibitor due to their properties like non-toxicity, biodegradability, and low cost. The use of natural gums as environmentally safe corrosion inhibitor for metal and alloys has in recent times received tremendous attention by several researchers. Also quantitative structure activity relationship approach has been used to establish the correlations between a number of quantum chemical parameters and the molecular structures of some gum extracts major components. This approach has aided in understanding the component of the gum extracts responsible for imparting the inhibition effect since there are several components of the gum which could act in synergy to inhibit the metal corrosion. This review paper presents an overview of works published on natural gums as green corrosion inhibitors. It also discusses the use of computational chemistry tools in understanding the inhibition mechanism of gum extracts components which is often difficult to determine using experimental means.

Investigation of Acetic Acid Corrosion Impact on Printed Solar Cell Contacts

In this paper, the corrosion mechanism behind damp heat-induced degradation of screen-printed silver front-side contacts of silicon solar cells due to the presence of acetic acid, which is known to be a decomposition product of the most common module encapsulation material ethylene vinyl acetate, is investigated. Scanning electron microscope (SEM) investigations and solder and peel-tests show that the interaction between screen-printed contacts and acetic acid results in a significant adhesion loss of the front-side metallization due to the corrosion of the glass layer inside the contacts. The application of a reductive potential to the front contact accelerates this process considerably and enables it at lower acetic acid concentrations. The analysis of the dissolved corrosion products of the contact (lead, silver) by chemical trace analysis (inductively coupled plasma optical emission spectrometry) and the generation of Pourbaix diagrams of lead in acetic acid enable the elaboration of a detailed model, which suggests a cycle of dissolution and subsequent reduction of the dissolved species as the mechanism behind the corrosion of the contacts in the model experiment and most probably in module application. Cyclic voltammetry measurements with acetic acid dipping solutions support this conclusion.

Corrosion Studies on Graphite Encapsulated FeCo Nanoparticles Modified Black Chrome (MBC) Spectrally Selective Coatings

Black chrome (BC) and graphite encapsulated FeCo nanoparticles modified black chrome (MBC) composite thin films were prepared on stainless steel substrates using electrodeposition technique under galvanostatic condition. Three different weight proportions of GE FeCo NPs, 0.025, 0.05, and 0.1 wt% in 200mL in black chrome electrolyte bath solutions were used for MBC thin film synthesis. A saline environment of 3.5% NaCl solution was used to carry out cyclic voltammetric and Tafel studies to understand the impact of corrosion on BC and MBC solar selective coatings. We carried out structural, microsctrucural, optical, vibrational and mechanical studies on these pristine (BC & MBC) and saline environment treated solar selective coatings. We observed that roughness and grain size of MBC solar selective surfaces decrease with increase in weight % of graphite encapsulated FeCo NPs during corrosion. More interestingly, after Tafel measurements, mechanical studies on MBC coatings showed enhanced hardness and Young’s modulus with respect to pristine BC coatings. Keywords: Electrodeposition; Black Chrome; Graphite encapsulated FeCo NPs, Solar selective coatings

Assessing Concurrent Uniform Corrosion of Aluminum Alloys As a Function of Temperature, pH, Time, and Chloride Ion Concentration

One of the greatest challenges for aircraft maintenance is localized corrosion induced fatigue and cracking, which is induced by aluminum alloys susceptibility to aggressive environment. Although pit growth kinetics was thoroughly investigated and nicely modeled by power law, the uniform corrosion impact on pit growth kinetics was ignored in the past, and therefore resulted in pit growth deviation from the ideal power law as indicated in a preliminary result. Uniform corrosion dissolved the surface material and thus induced reference plane recession and pit depth reduction. This non-trivial difference was proved to have a significant influence on pit growth modelling especially in high pH conditions. In this work, temperature and pH influence on uniform corrosion of 2024-T3, 6061-T6, and 7075-T6 aluminum alloys were reported through the free immersion test method. Extensive results performed in various pH (3 to 10), chloride concentration (0.01M to 1M), and temperatures (20⁰C to 80⁰C) from up to 1 month is reported to mimic real applications. A comparison with the weight loss experiment was demonstrated to provide a quantitative significance of pitting and uniform corrosion, respectively. Severity of uniform corrosion were measured and versus various pH, temperature, time, and chloride concentration. The key finding in this work was that uniform corrosion rate is oxygen-dependent with a dynamic influence of passivation. Therefore, to identify the contribution of oxygen and passivation (as affected by pH and temperature), experimental approaches including electrochemical impedance spectroscopy (EIS) and cathodic polarization were utilized. Furthermore, TEM images and electron diffraction were performed to assess the structure and morphology of the protective corrosion product driven by temperature. In addition, the Artificial Neural Network (ANN) modelling was employed to analyze the data obtained. A statistic-based model is able to recognize corrosion behavior pattern versus various conditions, therefore a prediction model can be generated according to the environmental inputs. In summary, the ultimate goal of this study is to suggest an effective maintenance for high value DoD and industrial assets according to an experiment-based prediction model and to understand the impact of different environmental parameters. In this study, a successful uniform corrosion predictive model was developed within specified conditions, which has a significant modification over pit depth growth. Therefore, a predictive model based on lab experimental data is applicable and an efficient low cost maintenance is doable.

Failure mode transitions of corroded deep beams exposed to marine environment for long period

This paper presents an investigation of the residual structural response of corroded, deep, reinforced concrete (RC) beams. A three-point loading test was carried out on two corroded deep beams that had been stored in a natural corrosive environment for 28years. Two uncorroded beams with the same steel configuration and span were tested to understand the impact of corrosion on the residual mechanical performance of the deep beams. The distribution of corrosion and gravimetric cross-section loss of the tension bars were measured. The corroded tension bars were extracted from the beams to study the residual mechanical properties. The load-bearing capacities of the corroded beams were assessed using the measured mechanical properties and the residual cross-section of the bars according to different failure mechanisms. The results show that, in this case, the corrosion of steel reinforcing bars could change the failure mode of the reinforced concrete beams from shear to flexure.

Corrosion fatigue assessment of creep-resistant magnesium alloy Mg–4Al–2Ba–2Ca in aqueous sodium chloride solution

Low corrosion resistance of magnesium alloys strongly limits their application range. This study aims at the investigation of corrosion influence on microstructure and depending mechanical properties of newly developed magnesium alloy Mg–4Al–2Ba–2Ca. The fatigue properties of this creep-resistant magnesium alloy were investigated under three corrosive environments: double distilled water, 0.01 and 0.1molL−1 NaCl solutions. Potentiodynamic polarization measurements and immersion tests were performed to estimate the corrosion behaviour. Specimen surfaces were observed using light and scanning electron microscopy for microstructure-related assessment of corrosion mechanisms. The corrosion fatigue behaviour was characterized in continuous load increase tests using plastic strain and electrochemical measurements. Continuous load increase tests allow estimating the fatigue limit and determining the failure stress amplitude with one single specimen. Fatigue results showed a significant decrease in the estimated fatigue limit and determined failure stress amplitude with increasing corrosion impact of the environments. This corrosion–structure–property relation was quantitatively described by means of model-based correlation approaches and failure hypotheses. Plastic strain amplitude and deformation-induced changes in electrochemical measurands can be equivalently applied for precise corrosion fatigue assessment.

Impact of corrosion on low-cycle fatigue degradation of reinforcing bars with the effect of inelastic buckling

The combined effect of inelastic buckling and chloride induced corrosion damage on low-cycle high amplitude fatigue life of embedded reinforcing bars in concrete is investigated experimentally. A total of forty-eight low-cycle fatigue tests on corroded reinforcing bars varied in percentage mass loss, strain amplitudes and buckling lengths are conducted. The failure modes and crack propagation are investigated by fractography of fracture surfaces using scanning electron microscope. The results show that the inelastic buckling, percentage mass loss and nonuniform corrosion pattern are the main parameters affecting the low-cycle fatigue life of reinforcing bars. It was found that the fatigue life of corroded reinforcing bars combined with inelastic buckling has a significant path dependency. The results show that in some cases the number of cycles to failure of corroded bars under constant amplitude fatigue test is increased.

A cast iron filings based model for dynamic investigation of corrosion and its compatibility with the real water distribution network

A new model for the investigation of the impact of corrosion on water quality, based on application of cast iron filings, is proposed. The use of filings ensures a large specific surface area which permits observation of changes in water quality in a relatively small amount of material. Two models differing in idea and construction are presented in this paper. The detailed results from the one model where thin layer water flows over the cast iron filings are shown. The rate of water quality changes during stagnant periods could be controlled by different amounts of filings. The results received in the model experiment are compared with those from a real fragment (100 m) of distribution system. Deterioration of water quality observed in model conditions is similar to that in real distribution network. Increase of iron concentration, turbidity, and decrease of oxygen and nitrate concentration were observed in both systems during stagnation periods. No changes of water quality were observed during flow conditions. Elemental and phase composition of corrosion scales collected from both systems was also comparable.

Impact of corrosion on sliding wear properties of low-alloyed carbon steel

Corrosion phenomena play an important role in limiting the lifetime of tribological systems. It is well known out of different studies that synergistic effects between mechanical sliding and corrosion often lead to increased volume losses when compared to their individual contributions. The aim of this work is to describe the tribological performance of low-alloyed C-steel under sliding/corrosion conditions at specific oxygen-free environments using CO2 atmosphere and brine. Low-alloyed C-steel was used as base material and was tribologically loaded in a novel close-to-reality test rig under reciprocating sliding contact against spray Ni-based coating counterpart. Additionally, pure sliding tests were carried out under N2 atmosphere with distilled water for comparison. Different microscopic methods were applied (e.g., SEM-FIB) for understanding the sliding/corrosion phenomena in addition to quantitative wear measurements by mass loss. The results show a significant influence of the microstructure on the tribological performance under sliding/corrosion conditions, where the formation of corrosion siderite layers (FeCO3) and their tribological properties plays a crucial role.

Impact assessment of metal corrosion on fuel reservoir carrying capacity

То prevent the large-scale contamination at the Vernadsky Station the development of the automated early-warning system of the leak fuel possibility is predicted in the State Target Scientific-Technical Research Program in the Antarctic for 2011-2020. An important соmроnent of the system is а subsystem of control and visualization the tensioned-deformed condition of the 200 m3 reservoir construction providing the lack of the necessary technical documentation and of data bу the current thicknesses both walls and welds of reservoir. The impact of corrosion from diesel fuel was studied on the carrying capacity of the conditional reservoir model (CRM). Using the finite elements method, which is implemented in software complex NASTRAN, the mathematical modeling was carried out of the CRM nonlinear behavior considering thinning of its wall in the system with protective capacity under the static loads action. Six options of the walls thinning were accepted in the various reservoir zones in 0.25, 0.5, 0.75, 1. 0, 1.25, 1.5 mm. Nonlinear calculations of the CRM both tension-deformed state and stability were carried out using the modified method of the incremental Newton-Raphson load. Studies have shown that thinning of the walls on 1.5 mm reduces the stock stability approximately in 30%, with the mахimum intensity for all options of wall thinning is observed in the lower zone of the СRМ with the protective capacity. The obtained results can bе immediately applied for analysis of the carrying capacity of the real reservoir construction after obtaining of the quantitative characteristics of the walls reservoir thicknesses and after the technical documenta­tion development for the real reservoir construction.

Stainless Steel for Dairy and Food Industry: A Review

Stainless steels (SS) were invented to overcome the problem of corrosion which is a major concern of food and many other industries. The alloy of steel containing iron-chromium-nickel is known as stainless steels. Stainless steels typically contain between 9 and 30 percent chromium and varying amounts of nickel, molybdenum, copper, sulfur, titanium, niobium, etc., may be added to obtain the desired mechanical properties and service life. Stainless steel is considered noble metal for use in dairy industry. Stainless steels are classified based on the chemical composition and it provides information to overcome many types of corrosion. Some of the limitations of SS employed in food and dairy industry are attack by lactic and malic acids at elevated temperature and poor thermal conductivity. However, these limitations may be overcome by carefully selection and fabrication, optimized operating condition, care and maintenance of the equipment. Stainless steels of various grades are widely used as engineering material for the fabrication of equipment. Stainless steels are corrosive resistant but under certain conditions the materials can stain and can corrode. Dairy and food industries are concerned with reliability of equipment and product purity. To achieve these, stainless steels are often the economical and practical materials of choice for process equipment. It is necessary to select most suitable grade of SS depending on the requirements for the specific application. The understanding of metallurgy and ways of fabrication are very essential to select right grade of SS. The food and dairy processing industries, corrosion becomes a critical factor directly influencing equipment and indirectly, overall equipment longevity. Key to minimizing corrosion impact needs better understanding of factors affecting corrosion as early as the equipment design phase and throughout subsequent processing operation.

Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

In this work, we have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. The FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly prepared joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.

Performance assessment of steel–concrete composite bridges with subsurface deck deterioration

In-service composite steel girder bridges typically experience a variety of deterioration mechanisms during their service lives, ranging from cracking, spalls, and delaminations in the reinforced concrete deck to corrosion in the steel girders. To date, several inspection techniques and novel technologies have been widely implemented to identify and measure different sources of defects associated with bridge systems, especially within the concrete deck. Despite successful implementation of these evaluation methodologies, what transportation agencies still lack is a fundamental understanding of the system-level behavior and the potential impact of the identified deterioration conditions on the overall performance of these bridges.In this paper, the impact of corrosion-induced subsurface deck delamination on the overall behavior and performance of steel–concrete composite bridges is investigated using finite element simulation and analysis. The accuracy and validity of the modeling approaches were assessed through a comparison to experimental data available in literature. A sensitivity study was performed to investigate the influence of deck deterioration on the system-level performance, load distribution behavior, and failure characteristics of two representative composite steel girder bridges. One of the selected structures is a full-scale laboratory bridge model, while the other one is an actual in-service structure with geometrical characteristics that represents typical features of steel girder bridges in Virginia.The selected damage scenarios included variations in different geometrical characteristics such as location and depth of damage, as well as degradation in material properties at the corresponding damaged areas. In addition to the bridge system behavior, the impact of rebar corrosion and subsurface delamination on the behavior of individual deck systems was investigated; while its implication on the current design methodologies for reinforced concrete decks was evaluated. Results from this investigation demonstrate that the deck deterioration has minimal impact on the overall system behavior and the path to failure of the selected structures, but may impact the failure characteristics in the form of reductions in the ultimate load-carrying capacity and system ductility.

A study on the applicability of Si in low-Mo duplex stainless steel weld metals to improve the corrosion resistance

The applicability of Si in low-Mo duplex stainless steel weld metals is examined in terms of corrosion resistance and impact toughness. Nano-secondary ion mass spectrometry and three-dimensional atom probe analysis indicate that Si is enriched at the outermost layer in the form of Si-oxide a few nanometer thick, leading to a significant increase in critical pitting temperature without sacrificing the impact toughness. Improved corrosion resistance suggests that the thin oxide layer possibly acts as a diffusion barrier against aggressive ionic species.

Imaging and Information Processing of Pitting-Corroded Aluminum Alloy Panels with Surface Metrology Methods

It has been established that corrosion is one of the most important factors causing structural deterioration, loss of metal, and ultimately decrease of product performance and reliability. Corrosion monitoring, accurate detection and interpretation are recognized as key enabling technologies to reduce the impact of corrosion on the integrity of critical aircraft and industrial assets. Interest in corrosion measurement covers a broad spectrum of technical approaches including acoustic, electrical and chemical methods. Surface metrology is an alternative approach used to measure corrosive rate and material loss by obtaining surface topography measurement at micrometer levels. This paper reports results from an experimental investigation of pitting corrosion detection and interpretation on aluminum alloy panels using 3D surface metrology methods, image processing and data mining techniques. Sample panels of AA 7075-T6, an aluminum alloy commonly used in aircraft structures, were coated on one side with a corrosion- protection coating and assembled in a lap-joint configuration. Then, a series of accelerated corrosion testing of the lap-joint panels were performed in a cyclic corrosion chamber running ASTM G85-A5 salt fog test. Panel surface characterization was evaluated with laser microscopy and stylus-based profilometry to obtain global and local surface images/characterization. Promising imaging and surface features were extracted and compared between the uncoated and coated panel sides, as well as on the uncoated sides under different corrosion exposure times. In the evaluation process, image processing, information processing and other data mining techniques were utilized. Information processing involves the steps of feature or Condition Indicator extraction and selection. The latter step addresses the problem of selecting those features that are maximally correlated with the actual corrosion state, for the purpose of corrosion detection, localization, quantification and state estimation. The results, verified by mass loss data, confirmed the contention that pits at the panel surfaces formed as a result of electrochemical corrosion attack, and showed that deteriorating pitting corrosion attack correlates with increasing corrosion exposure times. This study is a first step in the process of understanding, assessing and responding to the pitting corrosion and ultimately preventing material failure to insure aircraft structural integrity.

Stray Current Corrosion and Mitigation: A synopsis of the technical methods used in dc transit systems

© 2013 IEEE. As a result of the dynamic nature of the stray-current problem, it is challenging to control the stray current within allowable limits. However, with appropriate design decisions, meticulousness during construction, and a proper maintenance and testing regime, the stray-current leakage can be controlled within limits. The recent advances in the stray-current collection have also validated the use of a combination of mitigation methods and collection techniques for the control of stray current. The common application of this approach includes the use of rail boot and other design and construction mitigation techniques such as insulated fasteners, substation spacing in combination with steel reinforcement mesh, and a currentcollection technique. It can be concluded that although the technical advancements have been made in the mitigation and collection techniques for stray currents and new methods have been implemented by transit agencies, most of the mitigation methods used today are the same as suggested by the corrosion committees in the early 1920s. In transit agencies that have a regular maintenance and testing plan along with correctly designed mitigation measures, it was observed that they have a better handle on the stray-current leakage. This makes the regular testing of the tracks an important aspect, and this cost should be accounted in the transit agencies maintenance budget. In fact, assessment of the potential corrosion resulting from stray current should be a part of the planning and design process at the very inception of all projects and the testing of the stray-current corrosion must continue through the revenue service. Another aspect that was realized during the research is the need and importance of having trained corrosion-control staff on the transit agency payroll. Transit agencies are aware that stray current is a serious issue, and it would benefit them greatly if their staff is trained on the fundamentals of the stray current. This would not only help address any potential stray-current issues early on but would also aid the transit agency in conducting early testing of the rail track. Additionally, it was observed that the transit agencies are not keeping a log of the corrosion issues caused by the stray current and the money spent to mitigate those corrosion problems. This kind of tracking would be extremely beneficial to the rail industry in assessing the economic and logistic burden borne by rail transit agencies as a direct impact of stray-current corrosion. Stray-current issues have been around since the first electric railways were placed into operation and can create safety hazards and have serious effects on utility structures and the transit infrastructure itself. Since most of the heavily affected systems are street railways or trolleys, the areas in which the railways were built were also most likely to have underground metallic structures like utility piping, thus making it necessary to have stray-current leakage control. Although more of an issue in embedded tracks and tracks with low soil resistivity, stray-current corrosion is a concern for all kinds of track and needs to be addressed during the design, construction, and maintenance of dc-powered rail transit systems.

Iron–clay interactions: Detailed study of the mineralogical transformation of claystone with emphasis on the formation of iron-rich T–O phyllosilicates in a step-by-step cooling experiment from 90 °C to 40 °C

Iron–minerals–water interactions are of primary importance in the contexts of underground structure engineering (e.g. reactive barriers or deep geological storage) and for the understanding of secondary alteration processes in primitive meteorites. To improve our understanding of these systems, we determine the mineralogical transformations induced by the association of iron and silicates during a cooling through an experimental simulation of iron–clay interactions with a step-by-step procedure in the range of 90°C to 40°C. The run products and solutions are well characterised, by means of different techniques (X-ray diffraction, scanning and transmission electron microscopy, manocalcimetry, inductively coupled plasma optical emission spectrometry and ion chromatography), and the thermodynamic data concerning Fe-bearing phyllosilicates are well-tested comparing the modelling and experimental results. Therefore, the main mineralogical modifications observed include the remarkable formation of cronstedtite and greenalite, as well as the formation of magnetite at all temperatures, along with a significant dissolution of quartz, mixed-layer illite–smectite clays, illite (affecting more than 70% of each mineralogical phase) and a partial alteration of chlorite, kaolinite and dolomite. The experimental results confirm the reaction path predicted by thermodynamic modelling, i.e. the formation of iron-rich T–O phyllosilicates (cronstedtite and greenalite) and magnetite at the expense of metal iron and silicates. Both the experimental and thermodynamic results presented in this study provide important constraints to well predict the impact of nuclear waste canister corrosion in a claystone media and to better understand secondary alteration processes, which could also affect the mineralogical and chemical composition of primitive meteorites.