A lec­tur­er-cum-research sci­en­tist in the Mechan­i­cal Engi­neer­ing depart­ment at UTC’s Rober­val Lab­o­ra­to­ry, Julie Marteau is also in charge of the «Mate­ri­als and Tech­no­log­i­cal Inno­va­tions» course, one of the main objec­tives of which is to sup­port the devel­op­ment of inno­v­a­tive mate­ri­als and processes.

Anoth­er of the Department’s objec­tives is to iden­ti­fy tech­ni­cal solu­tions to the var­i­ous modes of degra­da­tion of mate­ri­als, depend­ing on their life expectan­cy and to mas­ter the choice of mate­ri­als and process­es, tak­ing into account tech­ni­cal, eco­nom­ic and envi­ron­men­tal con­straints, in order to design inno­v­a­tive products.

Julie Marteau’s research focus­es on two main areas. «The first area involves char­ac­ter­is­ing the rela­tion­ship between a material’s microstruc­ture and its local mechan­i­cal prop­er­ties. In oth­er words, dif­fer­ent exper­i­men­tal char­ac­ter­i­za­tion tech­niques are com­bined to inves­ti­gate the impact of using a spe­cif­ic process or the effects of mechan­i­cal stress. The aim is to study not only the sur­face, but also the core of the mate­r­i­al. The sec­ond area involves under­stand­ing func­tion­al­i­ty, in the broad­est sense, by char­ac­ter­is­ing the topog­ra­phy of a giv­en mate­r­i­al», she says.

Research aimed at under­stand­ing the syn­er­gy of local phe­nom­e­na to pro­duce a prod­uct with the tar­get­ed func­tion­al­i­ty. These research themes are of inter­est to a num­ber of aca­d­e­m­ic and indus­tri­al part­ners. Part­ners include Cetim, Raile­ni­um and com­pa­nies such as Arcelor­Mit­tal, Air­bus, RATP and BritishSteel.

Among the projects devot­ed to the inter­re­la­tion­ships between a material’s microstruc­ture and its mechan­i­cal prop­er­ties? «For exam­ple, a the­sis as part of FuseMet­al, a joint lab­o­ra­to­ry between Rober­val and Arcelor­Mit­tal, on the descrip­tion of the microstruc­ture gen­er­at­ed by weld­ing sheet met­al to under­stand how this will mod­i­fy the base mate­ri­als and how these will behave in terms of mechan­i­cal post-weld prop­er­ties, to see how the material’s behav­iour evolves after weld­ing. In this par­tic­u­lar case, the aim is to pro­duce a mate­r­i­al with high mechan­i­cal resis­tance and a cer­tain light­ness to reduce vehi­cle weight. We are also work­ing on the prob­lem of mechan­i­cal stress. For exam­ple, we have exam­ined the evo­lu­tion of the microstruc­ture of rails tak­en from rail­road tracks, after numer­ous train pas­sages. This enables us to under­stand and then pre­dict track wear process­es, always with a view to ensur­ing that the mate­r­i­al has the longest pos­si­ble ser­vice life. Final­ly, a project car­ried out in part­ner­ship with Cetim and sup­port­ed by the Region, in which a PhD the­sis is in progress, is devot­ed to the influ­ence of a new addi­tive man­u­fac­tur­ing process of friction/kneading on the microstruc­ture. The aim is to print dif­fer­ent parts in a tita­ni­um alloy, vary­ing the process para­me­ters in order to under­stand the impact of these vari­a­tions on the microstruc­ture gen­er­at­ed, and to estab­lish the link with the result­ing mechan­i­cal prop­er­ties. This new process belongs to the addi­tive man­u­fac­tur­ing fam­i­ly, but is based on sol­id-state depo­si­tion, which enables rapid depo­si­tion and there­fore greater cost­ef­fec­tive­ness », explains Julie Marteau.

Oth­er projects focus on sur­face topog­ra­phy, again always with a link to func­tion­al­i­ty. «In this case, for exam­ple, we analyse the effect of a sur­face treat­ment such as shot-blast­ing or pol­ish­ing on the sur­face fin­ish, and study the con­se­quences for a giv­en func­tion. This could be a change in the material’s hard­ness or gloss,» she assures us.

Among the projects linked to this very issue? «We have a project with the Muséum Nation­al d’Histoire Naturelle on “trace­ol­o­gy” applied to archae­ol­o­gy, which involves help­ing them to iden­ti­fy the wear and tear of cer­tain pre­his­toric flint tools: how the tools analysed may or may not have been used and under what con­di­tions? It’s then up to sci­en­tists to trans­late the results: uses, ges­tures… to enrich our under­stand­ing of pre­his­toric times. We also have a project, con­duct­ed in part­ner­ship with Cetim, which con­cerns the qual­i­fi­ca­tion and quan­tifi­ca­tion of “facies seizure wear «, she concludes.

Final­ly, a the­sis on the envi­ron­men­tal assess­ment of the imple­men­ta­tion and indus­tri­al­iza­tion of addi­tive man­u­fac­tur­ing process­es, co-direct­ed by Julie Marteau, Benoît Eynard and Raoud­ha Gaha Elka­mel, has begun recently.

MSD