Dissertationen zum Thema „Friction modification“

Předložená disertační práce se zabývá experimentálním studiem modifikátorů tření a maziv pro temeno kolejnice, které jsou aplikovány do kontaktu kola a kolejnice za účelem optimalizace adheze a redukce hluku. Hlavním cílem práce bylo objasnit vliv aplikovaného množství a složení těchto látek na adhezi v kontaktu. Hlavní pozornost byla věnována zejména potencionálním hrozbám souvisejících s kriticky nízkou adhezí, která může nastat po aplikaci těchto látek. Experimentální studium probíhalo v laboratorních i reálných podmínkách, konkrétně v tramvajovém provozu. V případě laboratorních experimentů byl využit komerční tribometr a dvoudiskové zařízení umožňující simulovat průjezd vozidla traťovým obloukem. Kromě samotné adheze bylo při experimentech sledováno také opotřebení a míra hluku. Výsledky ukázaly, že maziva pro temeno kolejnice jsou schopna poskytovat požadované třecí vlastnosti, nicméně jejich chování je silně závislé na aplikovaném množství. V případě předávkování kontaktu dochází ke kriticky nízkým hodnotám adheze, které vedou k výraznému prodloužení brzdné dráhy. V případě modifikátorů tření bylo ukázáno, že chování těchto látek je výrazně ovlivněno odpařováním základního média. Výsledky také ukázaly, že nadměrné množství částic pro modifikaci tření může způsobit kriticky nízké hodnoty adheze. U obou výše zmíněných typů produktů byl prokázán pozitivní vliv na míru opotřebení a míru poškození povrchu, zatímco významná redukce hluku byla dosažena pouze v případech, kdy došlo ke značnému poklesu adheze. V závěru této práce jsou uvedena doporučení pro další výzkumné aktivity v této oblasti.

An epoxy resin (Epon 828) was chemically modified with two different elastomers, poly(dimethyl-co-diphenyl) siloxane (PSX) and carboxyl-terminated butadiene-acrylonitrile (CTBN), to enhance its fracture toughness. The friction and wear of specimens modified with different amounts of elastomer were investigated in a pin-on-disk wear machine. An attempt was made to correlate the fracture toughness of the epoxy material to its fatigue wear rate for experiments in which a steel ball was sliding on a modified epoxy disk. A different type of experiment, modified epoxy pin sliding on an abrasive disk, was performed to detect whether abrasive wear of modified epoxies responds differently than fatigue wear to the fracture toughness. Other experiments were performed in which the wear debris produced during sliding was blown out of the interface to study its influence on friction and wear behavior. The effect of surface morphology on friction and wear was also studied. The results indicated that a marked improvement in fracture toughness was achieved for samples with higher elastomer content. Regardless of the type of the experiment, epoxy pin-on-abrasive disk or steel ball-on-epoxy disk, wear rates correlated positively with inverse of fracture toughness. Both friction coefficient and wear rate were found to be influenced by the removal of the wear debris, especially for samples with higher elastomer content. The friction coefficient was reduced for samples with higher elastomer content and this was attributed to the low surface energy of the elastomer. CTBN-modified epoxies exhibited lower friction coefficients than epoxies modified with polysiloxane. It was found that sample morphology had a significant effect on both friction coefficient and wear rate; the sample with approximately the same domain size but the least number of elastomeric domains exhibited the highest friction coefficient and the highest wear rate.
Ph. D.

This thesis investigates using friction stir welding to repair common surface defects found in aluminum-silicon sand castings. Wherein, the effect of welding parameters: weld RPM, weld speed, and number of weld passes, were evaluated using hardness, porosity density, welding temperature, microstructure refinement as metrics. Therefrom, the results strongly suggest friction stir welding: reduces porosity size, reduces porosity density in a specific area, increases average hardness, improves hardness uniformity, increases surface roughness, redistributes microstructure features in a manner that theoretically improves strength, and maintains a welding temperature less than 660 degrees Celsius.

Manufacturing more reliable and lighter body armour using the fabrics with high-performance fibres is the development trend of ballistic protection device. However,increasing the reliability of the body armour normally needs to increase weight. Thisinvestigation aims to develop better ballistic performance of body armour withoutaffecting weight. Inter-yarn friction in quasi-static state in fabrics constructed for bodyarmour is one of the important factors affecting ballistic performance. This researchfocuses on increasing inter-yarn friction by surface modification methods for superiorballistic protection of woven fabrics. Finite element (FE) simulation is employed toanalyse the effects of inter-yarn friction on ballistic performance theoretically. BothAPPCVD and sol-gel methods are used to achieve the purpose of practically increasinginter-yarn friction. Ballistic experiments are conducted to evaluate ballistic performanceof the fabrics with different levels of inter-yarn friction after treatments. Through both numerical and experimental investigation, it is confirmed that increasinginter-yarn friction in quasi-static state can improve ballistic performance of fabrics. Theoverall energy absorption will be increased with the increase of inter-yarn frictionbecause higher inter-yarn friction generates higher resistance to the projectile, makesfabric structure more stable, leads to more involvement of the secondary yarns andincreases both KE and FDE percentages. Moreover, higher levels of inter-yarn frictionwill flatten the trauma and make the fabric response more globalised owing to the lesstransverse deflection ability. However, over high inter-yarn friction is counterproductivebecause of stress concentration on the primary yarns. For the surface modification, one of the aramid yarns, Twaron® yarn and one of theUHMWPE yarns, Dyneema® yarn, and their fabric products are used as the substrates. SEM analyses are used to characterise the morphology changes. Both FTIR and EDXanalyses are conducted to identify the coated substance. Based on coefficients of friction test and yarn pull-out test, the APPCVD treatment and sol-gel treatment have been proved as two effective ways to increase inter-yarn friction and at the same time the tensile properties of the yarns and the weight are almost unaffected. Moreover, sol-gel treatment has been established as an effective method for improvingballistic performance without significant weight increase, where the energy absorption ofthe Dyneema® fabric can be increased by 6.74%, and the trauma depth can be decreased by16.99% for Twaron® fabric panel and by10.73% for Dyneema® fabric panel.

Friction modification within the wheel-rail interface is an important way of achieving ecologically friendly transportation of both persons and goods. This thesis aims to develop a new TOR lubricant, which will be able to maintain suitable frictional conditions while securing minimal adhesion required for traction. All measurements were carried out on tribometer MTM in the ball-on-disc configuration. In the first step, individual components were examined. More complex compositions were measured after that and the three best of them were compared with commercial TOR lubricants. The results show a good ability of developed compositions to maintain required adhesion, reduce wear, and all of them had resistivity against over-lubrication. Lastly, the process of lubricant verification before its application in real traffic was discussed.

Les films minces de Diamond-Like Carbon sont couramment employés dans les moteurs automobiles. Leur très faible coefficient de frottement et leur haute dureté permettent en effet d’optimiser les performances et la durée de vie des véhicules. Cependant, la plupart des lubrifiants utilisés dans les moteurs sont élaborés pour fonctionner avec des surfaces métalliques. Il est donc envisageable d’améliorer le comportement tribologique de films de DLC en leur conférant un caractère métallique par l’introduction d’éléments dopants en quantité limitée et contrôlée (15 % au maximum) dans la matrice de carbone amorphe. Un réacteur de dépôt industriel muni d’une technologie de dépôt hybride a été utilisé. Celle-ci combine la PECVD pour l’élaboration du DLC hydrogéné à la pulvérisation cathodique magnétron pour le dopage. Quatre éléments ont été introduits à différentes concentrations dans le DLC : aluminium, cuivre, molybdène et niobium. Les propriétés physico-chimiques des dépôts ont été caractérisées par XPS (composition et liaisons chimiques) et spectroscopie Raman (structure). La dureté, le frottement et l’usure à sec et en conditions lubrifiées, ainsi que l’énergie de surface des films ont également été caractérisés. Deux études in situ de tenue des DLC en température ont été conduites par spectroscopie Raman. Par comparaison avec un film de DLC pur, le dopage entraîne une modification de la structure du DLC, et par conséquent une réduction de la dureté des couches. Cependant, excepté dans le cas du cuivre, ceci s’accompagne d’une diminution significative du coefficient de frottement et de l’usure à sec des couches. En revanche, en dépit de ce résultat prometteur, l’impact sur les propriétés tribologiques en milieu lubrifié est plus modéré et fortement lié à la composition du lubrifiant employé. Enfin le transfert industriel du dopage a été étudié et validé dans le cas du dopage à l’aluminium
Diamond-Like Carbon thin films are commonly used in automotive engines. Thanks to their very low friction coefficient and high hardness, it is indeed possible to optimize the performances and the lifetime of vehicles. However, most of the lubricants that are used in engines are designed to be in contact with metallic surfaces. So it might be possible to improve the global tribological behaviour of DLC films by giving them a metallic character. This can be achieved with the introduction of doping elements in limited and controlled amount (maximum 15 at. %) in the amorphous carbon matrix. An industrial scale reactor has been used with a hybrid coating technology combining PECVD for the deposition of hydrogenated DLC and magnetron sputtering for the introduction of the dopants. Four elements have been tested with various amounts in the DLC: aluminium, copper, molybdenum and niobium. The physico-chemical properties of the films have been characterized by XPS (chemical composition and bonding) and Raman spectroscopy (structure). Hardness, friction and wear in both dry and lubricated conditions, and surface energy have also been determined. Two in situ studies under temperature have been conducted by Raman spectroscopy for deposited thin films. Compared to a pure DLC, doping led to a modification of the structure resulting in a decrease in hardness. However, except for copper doping, a significant reduction of friction and wear in dry conditions is observed. Despite this promising result, the impact of doping on lubricated tribological behaviour is limited and strongly dependent on the composition of the lubricant itself. Finally, the industrial transfer of DLC metallic doping has been studied and validated

For fiber-reinforced plastic composites, fiber-matrix adhesion is a significant aspect of composite properties. While conventional lightweight structures are always aiming for high fiber-matrix adhesion, innovative and unconventional functional constructions require different concepts. The research work treating adaptive fiber-reinforced plastic composites with shape memory alloy wires presented here uses the approach of actuators freely movable within the composite. This is supposed to prevent mechanical tensions in the interfaces of actuator and composite structure, which would otherwise cause damages of the composite. This work examines hybrid yarns based on friction spinning technology, with shape memory alloy wires as their core component as well as glass fibers, and partly polypropylene, as their sheath component. Additionally, the surface properties of the shape memory alloy wires being used are modified by sanding and coating. The results of a characterization by pull-out testing clearly show that a coating of the shape memory alloy wires with an abherent causes considerable decrease in adhesion and friction in the interface and leads to the mobility of the shape memory alloy wires in the later composite. An even greater effect is attained by sheathing the hybrid yarns in an additional layer of polypropylene, compacting the yarn cross-section. Thus, the pull-out force could be reduced to 35–40% of the reference structure.

This master thesis is focused on design and construction of laboratory shot peening machine. This machine is determined for modification of the topography of the friction surfaces specimens. Two types of specimens are used. The first specimen is sphere with diameter 20-40 mm. The second specimen is cylinder with 9.6 mm diameter. In this thesis the setting parameters of shot peening for creation of surface with the micro-texture was described. Influence of the micro-texture to the coefficient of friction was investigated under mixed lubrication and slip condition.

Developments in sport technology have been driven by competition and skiing is no exception. Skiing has evolved over many years making use of new materials and post-treatments methods, but in recent years progress has been limited. The low friction exhibited when sliding over snow and ice is governed by the tribological interaction between ski base and snow and the subsequent accumulation of a thin melt water film. The properties of new, innovative, blended ski base materials and post-treatment methods have been investigated using a range of methodologies. The incorporation of fluorinated hydrophobic silica nanoparticles into current ski waxes has been achieved. These nanoparticles have also been used as nano-abrasives to modify the physical surface structure of a ski base composed of ultra-high-molecular-weight polyethylene (UHMW-PE). Such polyethylene samples were also subjected to other physical treatment methods including abrasion with 120 grit, 800 grit sandpapers and 10-15μm silica particles combined with surface planing. The resultant surfaces were examined under a scanning electron microscope, contact angle tested and friction tested. The surface treatments which tended to be both physically and chemically hydrophobic were found to be beneficial at reducing friction in warm and wet snow conditions (snow temperature above -2°C). The addition of carbon black to UHMW-PE was also found to be beneficial in reducing static friction on snow. This was an interesting finding as the unmodified UHMW-PE was shown to be slightly more hydrophobic than UHMW-PE with added carbon from the contact angle evidence. Additionally, the visibly finer surface refinements with micro-scale to nano-scale features were also found to be more beneficial at reducing friction. A hydrophobic fumed silica, polydimethylsiloxane (PDMS), and perfluoropolyether (PFPE) were both blended with UHMW-PE to chemically modify the bulk material in contrast to traditional surface modification with hydrocarbon wax. PFPE, in particular, has been successfully blended with UHMW-PE to produce a novel base material for a downhill ski. Subsequent glide testing of skis, manufactured with this base material, in a range of conditions, demonstrated that the blended white base material closely matched the performance of skis with the current downhill black base material. The new blends also matched a hydrocarbon-waxed surface for hydrophobicity and were also found to be resistance to carbon coating at 5% levels of loading. Combined with the surface planing and nano scale abrasive structuring methods previously described, this novel base material has the potential to either compete or be a compliment to current wax treatment methods in order to achieve the small reductions of friction required to be successful in an alpine race.

Many of the flows in nature are turbulent. To modify turbulent flows, nature serves itself with different types of coatings. Sharks have riblets-like structures on their skin, fishes have slime with polymers and the surface of the lotus flower has superhydrophobic properties. However many times these naturally occurring coatings also serve other purposes. Due to millions of years of adaption, there are anyway many reasons to be inspired by these. The present work is an investigation of nature inspired coatings with the aim of passive flow manipulations. The goal of the investigation has not been to achieve drag reduction, but to achieve a better understanding of the effect of these coatings on turbulent flows. Simulations have been performed in a channel flow configuration, where the boundary condition on one wall has been modified. A macroscopic description has been used to simulate superhydrophobic and porous-like surfaces and a microscopic description has been used to simulate suspended fibers, both rigid and flexible, attached to the channel wall. For the macroscopic description, a pseudo-spectral method was used and for the microscopic description a lattice-Boltzmann method was used. The superhydrophobic modification was implemented using a general slip tensor formulation. In agreement with earlier results, drag reduction was achieved with slip in the streamwise direction and slip in the spanwise direction resulted in drag increase. Non-zero off-diagonal terms in the slip tensor resulted in a slight drag increase, but with rather similar flow behaviour. Transpiration, imitating a porous media, gave rise to drag increase and severely modified the turbulent structures, forming two-dimensional structures elongated in the spanwise direction. For the short fibers, neither rigid nor flexible fibers modified the velocity field to a large extent. The fibers gave rise to recirculation regions and these were seen to be stronger below high-speed streaks. Flexible fibers showed similarities to porous media through a coupling of wallnormal velocity and pressure fluctuations, and this was not seen for the rigid fibers. The fiber deflections were seen to correlate well with the pressure fluctuations.
Många naturligt förekommande flöden är turbulenta. Naturen har också gett upphov till flera typer av ytskikt som kan påverka dessa. Hajars skinn har räfflor, fiskar har slem som innehåller polymerer och lotusblommans yta har superhydrofobiska egenskaper, men ofta har dessa naturliga ytskikt också andra egenskaper. På grund av miljoner år av anpassning så finns det ändå många skäl att studera dessa. Detta arbete är en studie av naturinspirerade ytskikt, där målet har varit passiva flödesmanipulationer. Målet har inte varit att åstadkomma en ytfriktionsminskning, utan att få en bättre förståelse om hur dessa ytskikt påverkar turbulenta flöden. Simuleringar har utförts i en kanalliknande geometri, där en kanalväggs randvillkor har modifierats. En makroskopisk beskrivning har använts för att simulera superhydrofobiska och porösa ytor och en mikroskopisk beskriving har använts för att simulera fibrer, både stela och böjbara, fastsatta på en kanalvägg. För flödet med det makroskopiskt beskrivna randvillkoret har en pseudospektral metod använts och för flödet med det mikroskopiskt beskrivna randvillkoret har en lattice-Boltzmannmetod använts. Den superhydrofobiska ytan implementerades genom en generell tensorformulering. Ett randvillkor med nollskild hastighet i kanalens riktning gav upphov till en ytfriktionsminskning och ett randvillkor med nollskild hastighet vinkelrät mot kanalens riktning gav upphov till en ökad ytfriktion, i överensstämmelse med tidigare resultat. Nollskilda icke-diagonala tensorelement gav upphov till en smärre ökning av ytfriktionen, utan att nämnvärt förändra flödet. De porösa ytorna gav upphov till en ytfriktionsökning och hade stor inverkan på de turbulenta strukturerna. Dessa ytor bildade tvådimensionella struturer vinkelrät mot kanalens riktning. Varken de stela eller de böjbara fibrerna gav upphov till stora ändringar i hastighetsfältet. Däremot uppstor cirkulationszoner och dessa var starkare under stråkstrukturer med hög hastighet. De böjbara fibrerna uppvisade likheter med porösa material genom en interaktion mellan det vertikala hastighetsfältet och de turbulenta tryckfluktuationerna. Denna interaktion uppstod inte för de stela fibrerna. Fibrernas böjning korrelerade också i stor utsträckning till tryckfluktuationerna.

A commercial epoxy, diglycidyl ether of bisphenol-A, was modified by two different routes. One was the addition of silica to produce epoxy composites. Three different silane coupling agents, glycidyloxypropyl trimethoxy silane (GPS), -methacryloxypropyl trimethoxy silane (MAMS) and 3-mercaptopropyltriethoxy silane (MPS), were used as silica-surface modifiers. The effects of silica content, together with the effects of chemical surface treatment of silica, were studied. The results indicate that epoxy composites with silica exhibit mechanical and tribological properties as well as curing kinetics different than the pure epoxy. The optimum silica content for improved mechanical and tribological properties (low friction coefficient and wear rate) was different for each type of silane coupling agent. An unequivocal correlation between good mechanical and improved tribological properties was not found. Activation energy of overall reactions was affected by the addition of silica modified with MAMS and MPS, but not with GPS. The second route was modification by fluorination. A new fluoro-epoxy oligomer was synthesized and incorporated into a commercial epoxy by a conventional blending method. The oligomer functioned as a catalyst in the curing of epoxy and polyamine. Thermal stability of the blends decreased slightly at a high oligomer content. Higher wear resistance, lower friction coefficient and higher toughness were found with increasing oligomer content; thus in this case there was a correlation between good mechanical and improved tribological properties. The results indicated that increasing toughness and formation of a transfer film contribute to improved tribological performances.

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
The microstructural, mechanical and tribological properties of processed/textured structural steel surfaces, produced using a Friction Stir Welding (FSW) related procedure, called Friction Stir Processing (FSP), are analysed in this thesis. The surface of S275 and S690 structural steels samples was processed using two WC-Co pinless tools, with different diameters, and varying tool rotation and traverse speeds. The morphology of the surfaces, which is expected to have an important influence on its tribological behaviour, revealed to be very regular, for both materials, when processing with the lower diameter tool. Surface texture was also observed to evolve, according to the tool rotation to tool traverse speed ratio, for both substrates. Microstructural analysis of the processed surfaces revealed an important grain refinement in the stirred zone, independently of the material processed and of the processing conditions. The mechanical strength of the refined structures, evaluated trough hardness tests, was also found to drastically increase, relative to both substrates initial hardness. For the S275 steel, no hardness evolution was found when varying the tool traverse speed at a constant tool rotation speed. On the other hand, an important increase in surface hardness was found when increasing the tool rotation speed, i.e. when increasing the heat input during processing. For the S690 steel no important variation was found when varying, nor the tool rotation speed, nor the tool traverse speed. Both the grain refinement and the high hardenability of both steels, were found to be determinant for the hardness increase of the processed surfaces. Finally, the friction tests performed on S275 samples, revealed a 100% enhancement in the static friction coefficient, as well as in the assembly stiffness, of the processed surface relative to the unprocessed one.
Nesta tese, são analisadas a microestrutura bem como as propriedades mecânicas e tribológicas das superfícies de aços estruturais processadas/texturizadas por um processo baseado no Friction Stir Welding (FSW), denominado por Friction Stir Processing (FSP). As superfícies dos aços estruturais, S275 e S690, foram processadas por duas ferramentas de WC-Co, sem pino e de bases de diferentes diâmetros, variando em cada processamento, as suas velocidades de rotação e avanço. Espera-se que o comportamento tribológico das superfícies processadas seja influenciado pela sua morfologia, a qual revelou ser muito regular para ambos os materiais, quando processados pela ferramenta de menor diâmetro. Observou-se que a texturização da superfície variou com a relação das velocidades de rotação e de avanço da ferramenta, para ambos os substratos. A análise microestrutural das superfícies processadas revelou um importante refinamento de grão na zona processada, independentemente do material e das suas condições de processamento. A resistência mecânica das zonas processadas foi avaliada através de testes de dureza, sendo que se verificou que também esta aumentou drasticamente relativamente à dureza dos substratos. No caso do aço S275 não ocorreram variações da dureza para amostras processadas com a variação da velocidade de avanço da ferramenta, desde que se mantenha constante a sua velocidade de rotação. Contudo, verificou-se que, para a mesma velocidade de avanço da ferramenta, o aumento da velocidade de rotação, ou seja, o aumento do calor induzido pela ferramenta no substrato, aumenta a dureza obtida. No caso do aço S690, a dureza obtida não se alterou com a variação das velocidades de avanço e rotação da ferramenta. Quer a elevada temperabilidade dos aços, quer o seu refinamento de grão provaram ser determinantes no aumento da dureza das superfícies processadas. Finalmente, os testes de fricção realizados em amostras de S275, revelaram um aumento de 100% do coeficiente de fricção estática bem como na rigidez da ligação amostra/contra-corpo das amostras processadas relativamente às não processadas.

碩士
中華科技大學
土木防災工程研究所在職專班
100
Soil-nailins deep excavation construction methods that possess the characteristic of pull-back and deep-excavation have the advantages of no inner support needed and short construction period. These methods are widely adopted in engineering. Soil nail is one kind of pull-back element in pull-back- deep-excavation construction methods. The purpose of this study is to investigate the mechanical behavior of soil nail with ground modification on a large area deep excavation. With different ground modification cases, the numerical analysis has conducted to study the friction stress on soil-nailing. The results showed that during the excavation, the greater the excavation depth the more the friction stress on soil nail developed. The friction stress has influence by ground modification. At the initial excavation, the friction stress was contributed from the front area of the soil nail. The maximum friction stress presented at the point near the excavation surface. With the excavation depth progresses, the location of the peak values of friction stress will be deferred toward the end of the embedded area. When the excavation reached the bottom, the location of the maximum friction stress of the soil nails traveled to the end of the embedded area. At this point the end position elements of soil nails started to play a role and distributed the friction stress to the embedded end of the soil nail. Keywords: soil nails, ground modification, deep excavation, friction stress

碩士
中州科技大學
機械與自動化工程系
103
In this study, austempering ductile iron(ADI) was surface modified by friction stirring surface (FSS) to investigate the effects of friction stirring parameters on ADI surface characteristics. Therefore, parts of experiment were conducted with orthogonal arrays of Taguchi method for economically to explore the machining parameters on machining characteristics such as toughness, surface hardness, hardness depth, and roughness. Besides, through analysis of variance (ANOVA) and F test of signal to noise (S/N) ratio, the effects of friction stirring parameters such as rotation speed, feedrate, shoulder diameter, tilt angle, and probe diameter, and austempering temperature on ADI surface characteristics were determined. From this investigation, the relations between surface characteristics and friction stirring parameters of ADI via FSS were established. Furthermore, the significant degree of each parameters affected the surface characteristics were explored, and the optimal combination levels of the friction stirring parameters on toughness, surface hardness, and hardness depth was determined. Moreover, the experimental results could be applied in industrial applications and academic researches.

博士
國立成功大學
材料科學及工程學系
102
The current research aimed to explore the particle erosion of a die cast Al-14Si alloy ADC1C and ferritic ductile cast iron FCD450, and how the particle erosion behavior can be affected by modification of the microstructure via friction stir processing (FSP). In this study, perform FSP on die cast Al alloys by a conventional stirring tool with a pin, but ductile cast iron applied with no-pin tool. After specimens being stirred, evolution of matrix and second phase is investigated. Therefore, we discuss the different microstructure of different materials how to affect the erosion wear behaviors. The results indicate that friction stirring of the Al alloy can annihilate the dendritic structure of primary α-Al, break the eutectic Si and β-Al3(Fe,Mn)Si2 particles lengthwise, cause the eutectic Si particles to become more rounded, and blend the second phase particles rather uniformly in the α-Al matrix. According to the SiO2 particle erosion test, this microstructure modification improves the erosion resistance by not only second phase dispersion but also suppressing the opportunity of brittle cracking of the second phase particles. As for FCD450, the modified surface transformed to a thermal mechanical affected zone and a heat affected zone. The former includes elongated graphite, lenticular martensite and chunck-like or film-like retained austenite. The heat affected zone close to the thermal mechanical affected zone maintains nodular graphite and the similar matrix as the above. However, the farther reveals the hard-eye structure. The results of erosion test on ductile iron indicate that the modified surface reveals better erosion resistance at oblique impact; owing to the hard, brittle martensite and elongated graphite. However surface modification does not improve the erosion resistance at high angle impact. The friction stirred cast iron depicts maximum erosion rate at 30° and 60° impact, where the former is governed by ductile erosion and the latter by the brittle effect.