1. Microstructure and mechanical performance of AISI D2 tool steel after standard and modified deep cryogenic treatmentVenu Yarasu, Bojan Podgornik, Barbara Šetina, Marko Sedlaček, Črtomir Donik, Francisco Ruiz-Zepeda, 2025, izvirni znanstveni članek Ključne besede: steel, isothermal heat treatments, cyclic response, martensite, fracture toughness
Objavljeno v DiRROS: 23.05.2025; Ogledov: 214; Prenosov: 95
 Celotno besedilo (26,64 MB)
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2. Combining ultrafast laser texturing and laser hardening to enhance surface durability by improving hardness and wear performanceAbhijit Cholkar, Suman Chatterjee, Sujith Kumar, Marko Sedlaček, Bojan Podgornik, David Kinahan, Dermot Brabazon, 2024, izvirni znanstveni članek Povzetek: Aluminum alloy 7075 is utilized widely across marine, aerospace, and automotive sectors. However, its surface wear resistance has hindered its application in certain tribological environments. Addressing this challenge, the current study examines a hybrid laser method to increase surface wear resistance by combining two techniques: ultrafast laser texturing and laser-based surface hardening. Ultrafast laser processing is conducted using 3 W laser power, 100 kHz pulse repetition rate, 4 mm s-1 scanning speed, and three different scan patterns. After the texturing operation, laser-based surface hardening is then performed on these textures using a continuous wave laser. The laser heat treatment is conducted using laser powers of 400 and 500 W with three different scan speeds of 1, 2, and 3 mm s-1 . Microhardness evaluations show a notable increase in hardness, with the hardest sample exhibiting a 17.8% increase compared to the pristine sample. The lasertextured and laser heat-treated samples exhibit a significant reduction in the average coefficient of friction and wear volumes compared to samples that were laser-textured but not laser heat-treated. The investigated laser processing strategy offers a promising approach for surface modification, enhancing both mechanical properties and wear resistance of aluminum alloy 7075 surfaces.
Ključne besede: hardness, laser hardening, parametric modeling, surface modification, ultrafast laser texturing, wear resistance
Objavljeno v DiRROS: 05.11.2024; Ogledov: 377; Prenosov: 847
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3. Characterization of micro-threaded stem taper surface of cementless hip endoprosthesesDrago Dolinar, Boštjan Kocjančič, Klemen Avsec, Barbara Šetina, Aleksandra Kocijan, Matjaž Godec, Marko Sedlaček, Mojca Debeljak, John T. Grant, Timon Zupanc, Monika Jenko, 2024, izvirni znanstveni članek Povzetek: We investigated micro-threaded stem taper surface and its impact on premature failures, aseptic loosening, and infection in cementless hip endoprostheses. Our study focused on the fretting, and crevice corrosion of micro-threaded tapers, as well as the characterization of the microstructure and surface properties of two new and three retrieved Zweymüller stem tapers. The retrieved samples were selected and examined based on the head–stem taper interface being the sole source of modularity with a metallic component, specifically between the Ti alloy taper stem and the ceramic head. To determine the surface chemistry and microstructures of both new and retrieved hip endoprostheses stem taper titanium alloy, scanning -electron microscopy (SEM) was employed for morphological and microstructural analyses. Energy dispersive spectroscopy (EDS) was utilized for characterizing chemical element distribution, and electron backscattered diffraction (EBSD) was used for phase analysis. The roughness of the micro-threated stem tapers from different manufacturers was investigated using an optical profilometer, with standard roughness parameters Ra (average surface roughness) and Rz (mean peak to valley height of the roughness profile) being measured. Electrochemical studies revealed no fretting corrosion in retrieved stem tapers with ceramic heads. Consequently, three retrieved tapers and two new ones for comparison underwent potentiodynamic measurements in Hank’s solution to determine the corrosion rate of new and retrieved stem taper surfaces. The results showed a low corrosion rate for both new and prematurely failed retrieved samples due to aseptic loosening. However, the corrosion rate was higher in infected and low-grade infected tapers. In conclusion, our study suggests that using ceramic heads reduces taper corrosion and subsequently decreases the incidence of premature failures in total hip arthroplasty.
Ključne besede: total hip arthroplasty, stem micro-threaded taper, taper surface morphology, microstructure, corrosion, Ti implant alloy
Objavljeno v DiRROS: 06.06.2024; Ogledov: 2490; Prenosov: 495
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4. Sliding wear behaviour of conventional and cryotreated PM Cr-V (Vanadis 6) ledeburitic tool steelVenu Yarasu, Peter Jurči, Peter Gogola, Bojan Podgornik, Marko Sedlaček, 2023, izvirni znanstveni članek Ključne besede: cold work tool steel, conventional treatment, cryogenic treatment, hardness, reciprocal sliding, wear
Objavljeno v DiRROS: 08.04.2024; Ogledov: 950; Prenosov: 162
 Celotno besedilo (7,85 MB)
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5. Influence of precipitation hardening on the mechanical properties of Co-Cr-Mo and Co-Cr-W-Mo dental alloysMarko Sedlaček, Katja Zupančič, Barbara Šetina, Borut Kosec, Matija Zorc, Aleš Nagode, 2023, izvirni znanstveni članek Ključne besede: Co-Cr alloys, microstructure analysis, hardness, wear resistance
Objavljeno v DiRROS: 01.02.2024; Ogledov: 1035; Prenosov: 488
Celotno besedilo (53,05 MB)
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6. Influence of boron and nitrogen on the machinability, polishability and wear of martensitic stainless steelsMarko Sedlaček, Barbara Šetina, Vesna Žepič Bogataj, Jaka Burja, 2023, izvirni znanstveni članek Ključne besede: martensitic stainless steel, boron, nitrogen, wear, machinability, polishability
Objavljeno v DiRROS: 01.02.2024; Ogledov: 841; Prenosov: 394
Celotno besedilo (7,53 MB)
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7. High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V contentBojan Podgornik, Marko Sedlaček, Barbara Šetina, Miha Čekada, 2023, izvirni znanstveni članek Ključne besede: (Cr, V)N coating, galling, high-temperature tribology, hot forming, self-lubrication
Objavljeno v DiRROS: 26.01.2024; Ogledov: 817; Prenosov: 454
Celotno besedilo (12,53 MB)
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