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Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys
Cremer, L. 2025. Towards patient-specific articulating implants: Wear properties of polymeric materials on additively manufactured metallic alloys. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/29da81c3-79a0-419b-a4ab-b8...
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613792502808576 |
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| access_status_str | Open Access |
| author | Cremer, Labau |
| author2 | Van der Merwe, Johan |
| author_browse | Cremer, Labau Van der Merwe, Johan |
| author_facet | Van der Merwe, Johan Cremer, Labau |
| author_sort | Cremer, Labau |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Cremer, L. 2025. Towards patient-specific articulating implants: Wear properties of polymeric materials on additively manufactured metallic alloys. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/29da81c3-79a0-419b-a4ab-b8256e4bfd81 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132113 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:41:46.856Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132113 Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys Cremer, Labau Van der Merwe, Johan Becker, Thorsten Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Implants, Artificial -- Biocompatibility Additive manufacturing Mechanical wear -- Testing UCTD Alloys -- Testing Cremer, L. 2025. Towards patient-specific articulating implants: Wear properties of polymeric materials on additively manufactured metallic alloys. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/29da81c3-79a0-419b-a4ab-b8256e4bfd81 Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: The growth of additive manufacturing (AM) in the biomedical industry, particularly for joint implants, has enabled the production of implants previously unattainable with conventional methods, potentially extending implant longevity. This is particularly significant, as recent trends indicate that joint implant procedures are increasing among younger age groups. AM Ti-6Al-4V is known to be biocompatible and is well established in the AM-field, however, when left untreated, it exhibits low wear resistance. To address this, surface hardening techniques such as thermal oxidation has shown promise, whereby a hard, wear resistant oxide layer is grown on the articulating surface. However, the oxide layer is prone to delaminate and there are few studies that have improved and developed thermal oxidation treatments for AM Ti-6Al-4V. Furthermore, there is a lack of preclinical wear assessment of surface hardened AM Ti-6Al-4V against the polymers used in joint implants. This study aims to investigate the wear between AM-produced metallic alloys on polymeric materials, for intended use in patient-specific metallic articulating implants. Multidirectional pin-on-plate wear testing was used to assess wear, by using loading conditions that simulate those of articulating implant components. In addition, project objectives focused on assessing the feasibility of improving the wear performance of AM Ti-6Al-4V, by making use of thermal oxidation. Consequently, the project set out by testing the current post manufacturing processes and manufacturing methods used for patient-specific implants, in South Africa. It was found that the single step thermal oxidation process of AM Ti-6Al- 4V led to cases of delamination due to a small oxygen diffusion zone below the oxide layer of 1-2 μm. To address this, a boost-diffusion heat treatment was developed to enhance oxide layer adhesion in AM Ti-6Al-4V, by diffusing oxygen up to 215 μm deep into the substrate. Hardness values achieved were up to three times greater than the bulk hardness below the oxide layer, gradually decreasing to match the bulk hardness. Following the development of the boost-diffusion heat treatment, its wear properties were assessed over a cross-shear range of 0 to 0.3 and contact stress ranges of 0.56 to 14 MPa. A method was presented to simplify the parameter selection process for a multidirectional wear machine and allow for more easily testing the wide range of loading conditions. Wear testing of cross-linked Ultra- High-Molecular-Weight Polyethylene (UHMWPE) against boost-diffused treated AM Ti-6Al-4V revealed that wear was higher than expected, due to elevated surface roughness. Continued wear testing led to an improved surface finish, resulting in a reduction in the dynamic friction coefficient, thus enhancing overall wear performance. Untreated Ti-6Al-4V showed signs of severe surface degradation, highlighting the improved abrasion resistance achieved through the boost-diffusion treatment. Future work was identified, with an initial focus on reducing the surface roughness of boost-diffusion-treated AM Ti-6Al-4V. This improvement could lead to better wear performance by reducing friction and third body wear, whilst still leveraging the added benefits of the thermal oxide layer. AFRIKAANSE OPSOMMING: Die groei van laagvervaardiging (LV) in die biomediese industrie, veral gewrigsimplantate, het die produksie van implantate moontlik gemaak wat voorheen nie mootlik was met konvensionele vervaardigings metodes, wat potensieel die lewensduur van implante kan verleng. Dit is veral belangrik, aangesien onlangse tendense dui op 'n toename in gewrigsimplantaat prosedures onder jonger ouderdomsgroepe. LV Ti-6Al-4V is bio-versoenbaar en is goed gevestig in die laagvervaardigingsbedryf. Wanneer dit onbehandeld gelaat word in ‘n slytasie omgewing, toon dit ongewensde degenerasie van die artikulerende oppervlakte. Om hierdie probleem aan te spreek, word oppervlakverhardingstegnieke soos termiese oksidasie gebruik, waardeur 'n harde, slytasiebestande oksiedlaag op die artikulerende oppervlak gegroei word. Die oksiedlaag is egter geneig om te delamineer, en daar is min studies wat termiese oksidasiebehandelings vir LV Ti-6Al-4V verbeter en ontwikkel. Daar is ook 'n gebrek aan pre-kliniese slytasietoetse van oppervlakverharde LV Ti-6Al-4V op die polimere wat in gewrigsimplantate gebruik word. Hierdie studie beoog om die slytasie tussen LV-geproduseerde metaallegerings op polimere materiaal te ondersoek vir potesiële gebruik in pasiënte-spesifieke metaal artikulerende implantate.‘n Multidimensionele pin-op-plaat slytasietoestel is gebruik om slytasie te assesseer deur gebruik te maak van beladingstoestande wat dié van artikulerende implantaat komponente simuleer. Daarbenewens het die projekdoelwitte gefokus om te bepaal of termiese oksidasie van LV Ti-6Al-4V ‘n bruikbare oplossing is vir verbeterde slytasiekenmerke. Gevolglik het die projek begin deur die slytasie van huidige produksie prosesse en vervaardigingsmetodes te ondersoek wat gebruik word vir pasiënte-spesifieke implantate in Suid-Afrika. Dit is bevind dat die enkelstap termiese oksidasieproses van LV Ti-6Al-4V gelei het tot gevalle van delaminasie weens 'n klein suurstofdiffusiegebied onder die oksiedlaag van 1-2 μm. Om hierdie probleem aan te spreek, is 'n gevorderede diffusie hittebehandeling ontwikkel om die hegtingseienskappe van die oksiedlaag in LV Ti-6Al-4V te verbeter, deur suurstof tot 215 μm diep in die substraat te diffundeer. Hardheidswaardes van sowat drie keer groter as die omvangshardheid is bereik onder die oksiedlaag, wat geleidelik afgeneem het tot die omvangshardheid. Na die ontwikkeling van die gevorderde diffusie hittebehandeling is die slytasieeienskappe daarvan geassesseer oor 'n kruis-skuifreeks van 0 tot 0.3 en kontakdrukreeks van 0.56 tot 14 MPa. 'n Metode is ontwikkel om die parameterkeuseproses vir 'n multidimensionele pin-op-plaat slytasietoestel te vereenvoudig en ook om makliker ‘n wye reeks lastoestande te toets. Slytasietoetse van kruisgebinde Ultra-Hoë-Molekulêre-Gewig Poliëtileen (UHMWPE) teen die gevorderde diffusie hittebehandelde LV Ti-6Al-4V is uitgevoer. Hoër as verwagte slytasie is waargeneem weens verhoogde oppervlakgrofheid. Uitgebreide slytasietoetse het gelei tot verbeterde oppervlakgrofheid, wat 'n vermindering in die dinamiese wrywingkoëffisiënt tot gevolg gehad het, en sodoende is die algehele slytasie eienskappe verbeter. Onbehandelde Ti-6Al-4V het tekens van erge oppervlakdegenerasie getoon. Die gevorderde diffusie hittebehandeling het egter minimale oppervlakdegenerasie gewys, wat verder die verbeterde slypweerstand beklemtoon wat deur die gevorderde diffusie hittebehandeling bereik is. Voortvloeiende navorsing is geïdentifiseer met 'n aanvanklike fokus, om die oppervlakgrofheid te verminder na afloop van die gevorderde diffusie hittebehandeling op LV Ti-6Al-4V. Hierdie verbetering kan lei tot beter slytasie gedrag deur wrywing en derde-liggaam slytasie te verminder, terwyl die voordele van die termiese oksiedlaag steeds behoue bly. Doctoral 2025-05-23T18:39:19Z 2025-05-23T18:39:19Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132113 Stellenbosch University xx, 164 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Implants, Artificial -- Biocompatibility Additive manufacturing Mechanical wear -- Testing UCTD Alloys -- Testing Cremer, Labau Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title | Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title_full | Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title_fullStr | Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title_full_unstemmed | Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title_short | Towards patient-specific articulating implants: wear properties of polymeric materials on additively manufactured metallic alloys |
| title_sort | towards patient specific articulating implants wear properties of polymeric materials on additively manufactured metallic alloys |
| topic | Implants, Artificial -- Biocompatibility Additive manufacturing Mechanical wear -- Testing UCTD Alloys -- Testing |
| url | https://scholar.sun.ac.za/handle/10019.1/132113 |
| work_keys_str_mv | AT cremerlabau towardspatientspecificarticulatingimplantswearpropertiesofpolymericmaterialsonadditivelymanufacturedmetallicalloys |