Point-of-care testing brings diagnosis and treatment monitoring to the site of the patient. It heavily relies on biosensors, which leverage the interactions between a target biomarker and a bioreceptor, to deliver fast and accurate results. However, non-specific binding of molecules and microorganisms on the biointerface can interfere with biomarker-bioreceptor interactions and diminish a biosensor’s sensitivity, specificity, and stability. In turn, this can lead to false diagnoses and ineffective treatments. Omniphobic-lubricant infused (OLI) coatings exhibit slippery, self-cleaning characteristics that repel untargeted molecules and microorganisms to augment the biosensor’s performance. In this work, we investigate the proficiency of OLI coatings in two specific applications: dissolved oxygen sensing and DNA biosensing. First, in water quality monitoring, an OLI coating is applied to the selectively permeable membranes of a dissolved oxygen sensor. Over a three-week incubation period in an environment with accelerated bacterial growth, the coated membranes exhibit a 160% higher reproducibility (10% deviation in sensitivity) and lower biofilm formation (96° static contact angle) in comparison to unmodified membranes (26%, 32°). The second application is in DNA biosensing, where a novel OLI coating uses carbon dioxide plasma activation to embed oligonucleotide probes. It demonstrates an optimized balance of slippery repellency (76° static contact angle, 10° sliding angle) and biosensing functionality, 19% longer clotting times than conventional blocking conditions, and equal sensitivity to PLL-PEG when capturing target DNA in whole blood. Going forward, our research will continue to expand the use of OLI coatings in biosensing applications, particularly exploiting its antibiofouling and anticoagulative capabilities. / Thesis / Master of Applied Science (MASc) / Biosensors are an integral tool in delivering quick and accurate point-of-care diagnosis and treatment monitoring. However, their performance can be impeded by the non-specific binding of undesirable molecules and microorganisms on the sensing surface. Omniphobic lubricant-infused (OLI) coatings have been shown to suppress biofouling and blood clotting on surfaces through exceptional repellency. This thesis focuses on the implementation of OLI coatings in biosensing applications. It investigates the antibiofouling capacity of an OLI coating on a membrane for dissolved oxygen detection. Then, it discusses a novel coating with integrated DNA biosensing functionality for working directly with blood samples. The enclosed work demonstrates that the OLI coating empowers biosensors to deliver more effective point-of-care testing.

No / This paper aims to establish the acid concentration of finely dispersed droplets in hydrocarbon oils. Small quantities of aqueous sulphuric acid (H2SO4) were found to be trapped within hydrocarbon shells, making them inaccessible for concentration evaluation by titration. Fourier transform infrared spectroscopy (FTIR) used in the attenuated total reflection mode (ATR; FTIR-ATR) was applied to study the reaction products of squalane, C30H62, and an API Group I base oil with various concentrations of aqueous H2SO4. The absorbance comparison usually used for estimating acid concentrations was found to fail when small quantities of acid are trapped in the reaction product. It was found that the peak shift and changes in absorbance found for various pure aqueous acid concentrations were useful to establish the remaining concentration of the trapped H2SO4. This paper fulfils the identified need to study acid dissociation-dependent peak shifts of H2SO4 to find the acid concentration of finely dispersed droplets in hydrocarbon oils.

No / Physical and mechanical properties for prealloyed 6061 Al powder processed with and without additions of solid and/or liquid lubricants and sintering aids (Pb, Sn, Ag) are presented. For comparison, both vacuum and nitrogen sintering were carried out on as received (gas atomised) and degassed powder compacts pressed at 340 and 510 MPa. Vacuum degassing of the prealloyed powder provided better compressibility and thus higher green densities than those for the as received powder. Highest sintered densities of ~98-99% of theoretical were obtained for the prealloyed (and degassed) Al compacts by sintering under pure nitrogen with an addition of 0·6 wt-% paraffin wax as solid lubricant or 1·33 vol.-% liquid paraffin, or with a 0·12wt-%Pb addition as sintering aid and no lubricant. It was found that additions of solid lubricants such as lithium stearate and acrawax to both the premixed (elemental) and prealloyed powders provided reasonable green densities of ~94·5-95·5% TD, but had deleterious effect on sintered densities and microstructures, particularly under vacuum sintering. Other lubricants such as zinc stearate, stearic acid and liquid paraffin provided similar green densities, but higher sintered densities and less porous microstructures, particularly by sintering under pure nitrogen. The prealloyed compacts sintered under pure nitrogen consistently provided much higher sintered densities than elementally premixed compacts sintered under pure nitrogen or vacuum. It is therefore concluded that both lubricant type and sintering atmosphere will have a major effect on the sintered properties of the 6061 Al powder. Sintering under pure nitrogen resulted in higher sintered densities as compared with vacuum sintering for this grade of Al alloy. Tensile properties of the degassed and vacuum sintered (and T6 tempered) prealloyed powder compacts were higher than those of the equivalent alloy prepared by elemental mixing and comparable with those of the commercial (wrought) 6061 Al alloys.

Non-wetting surfaces mainly categorized into superhydrophobic (SHS), lubricant-infused (LIS) and solid-infused surfaces (SIS), by virtue of their superior water repellant properties have wide applications in several energy and environmental systems. In this dissertation, the role of non-wetting surfaces toward the enhancement of condensation effectiveness is analyzed by taking into consideration the tube side and shell side individual interfacial energy transport processes namely, drag reduction, convection heat transfer enhancement, fouling mitigation and dropwise condensation heat transfer. First, an analytical solution is developed for effective slip length and, in turn, drag reduction and friction factor on structured non-wetting surfaces. Secondly, by combining the solution for effective slip length on structured non-wetting surfaces and the fractal characterization of generic multiscale rough surfaces, a theoretical analysis of drag reduction, friction factor, and convection heat transfer enhancement is conducted for scalable non-wetting surfaces. Next, fractal representation of rough surfaces is used to theoretical derive the dropwise condensation heat transfer performance on SHS and novel SIS surfaces. The aspect of dynamic fouling mitigation properties of non-wetting surfaces is explored by conducting systematic experiments. Using Taguchi design of experiments, this work for the first time presents a closed formed relationship of fouling mitigation quantified in terms of asymptotic fouling resistance with Reynolds number, foulant concentration and viscosity of the infusion material that represents the different surface types in a unified manner. Furthermore, it was observed that LIS and SIS offer excellent fouling mitigation compared to SHS and conventional smooth surfaces, however only SIS owing to the presence of solid-like infusion materials is observed to be robust for practical applications. / Doctor of Philosophy / Inspired by the naturally occurring water repellant lotus leaf and pitcher plant, metallic surfaces have undergone engineering modifications to their native wetting properties. By generating roughness features ranging from nanometer to micrometer length scales, subjecting them to low surface energy treatments and by choosing an appropriate water repellant infusion material, the water repellant properties seen on lotus leaf and pitcher plant can be engineered. Such water repellant (non-wetting) surface fabrication methods are widely available in the literature however very few are scalable to surface types (e.g. copper, aluminum etc.), surface size (millimeters to meters) and shape (plain, curved, inside of tubes etc.). In this work, considering scalable fabrication methods such as electrodeposition and chemical etching, a systematic analysis is conducted on enhancement of four interfacial processes that are a part of many industrial applications. First, the extent of water repellency by structured non-wetting surfaces for the flow of fluid (water) quantified in terms of effective slip length of flow is analytically derived. Using this theory and a self-similar (fractal) nature of the more generic rough surface designs, a theoretical analysis into the drag reduction, convection heat transfer enhancement on non-wetting surfaces is conducted. Next, using the fractal nature of the rough superhydrophobic surfaces (SHS) a theoretical investigation into dropwise condensation performance is used to derive bounds on condensation heat transfer enhancement. Through systematic experimental investigations, it is shown that a solid-infused surface (SIS) and lubricant-infused surfaces (LIS) which, respectively, incorporate a polymer and a slippery lubricant in the interstitial region of metallic asperities, exhibit superior dynamic mineral fouling mitigation performance compared to SHS and conventional smooth surfaces. In addition, it is demonstrated that SIS is a far robust and durable choice when compared to LIS for use in the long run.

Superhydrophobic and lubricant-infused porous surfaces are two classes of non-wetting surfaces that are inspired by the adaptation of natural surfaces such as lotus leaves, pond skater legs, butterfly wings, and Nepenthes pitcher plant. This dissertation focuses on fabrication and in depth study of bioinspired functional metallic surfaces for applications such as power plant condensers and marine applications. Toward that, first, facile and scalable methods are developed for the fabrication of superhydrophobic surfaces (SHS) and lubricant-infused surfaces (LIS). Second, the corrosion inhibition mechanism of SHS was systematically studied and modeled via electrochemical methods to elucidate the role of superhydrophobicity and other parameters on corrosion inhibition. The anti-corrosion properties of SHS and LIS were systematically studied over a range of temperatures (23°C–90°C) to simulate an actual condenser environment. Moreover, the environment of application often involves using harsh cleaning chemicals. The fabricated non-wetting surfaces were examined over a wide range of acidity and basicity (pH=1 to pH=14). Third, the durability of SHS and LIS is systematically assessed using a set of testing protocols including water impingement tests, scratch wear tests, and accelerated chemical corrosion tests. Considering that industrial environments of application are often turbulent, in addition to static long term corrosion tests, long term dynamic durability was studied in a simulated turbulent condition. Fourth, the performance of the fabricated nonwetting surfaces was systematically studied against calcium sulfate scaling in turbulent conditions and different temperatures. An analytical relationship based on the Hill-Langmuir model is proposed for the prediction of fouling on nonwetting and conventional surfaces alike in dynamic conditions. Overall 1048 individual samples were studied via over 3000 measurements in this dissertation to establish a comprehensive fundamental knowledge base on fabrication and anti fouling characteristics of metallic nonwetting surfaces, which profoundly helps to design appropriate surfaces and fabrication methods based on the use environment. / Doctor of Philosophy / Metallic surfaces such as copper, brass, and aluminum are everywhere in our daily lives. From tumblers, household pipes to the bank of tubes in power plants condensers. Fouling of these surfaces has significant performance and economic impact. Scaling is a type of crystallization fouling like the familiar limescale everyone is familiar to see around the surface of a house kettle. Corrosion is another type of fouling and is detrimental to metallic surfaces. For example, 50% of water consumption in the U.S. is being used in thermo-electric power plants where fouling of metallic surfaces will impede the flow of working fluid, therefore increasing power needed for pumping, decrease efficiency, and decrease ultimate lifetime. One study in 2019 shows corrosion costs 3% of the gross national products of China and it is already known to be similar for other major economies like the USA, which is a hefty cost. Nature has inspired a lot of solutions for mankind. In this work, inspired by natural surfaces such as lotus leaves, butterfly wings, and pond skater legs, a class of superhydrophobic surfaces (SHS) was fabricated. Moreover, a closer look at how the complex human body puts everything in order exposes one of its most striking and essential characteristics: how wet and lubricated its interfaces are. Our lungs, eyes, joints, intestine, bones; either hairy or porous, all are lined wet surfaces that work as fouling inhibitors and defect free surfaces. This also have been observed elsewhere such as on Nepenthes pitcher plant. Inspired by these, another class of non-wetting surfaces, lubricant-infused surfaces (LIS) was fabricated. This dissertation for the first time investigates a rational methodology in the fabrication of metallic SHS and LIS and their anti-scaling and anti-corrosion properties in different environments of application, including a range of temperature (23°Câ€"90°C), various solutions (pH=1 to pH=14), and long-term static and dynamic (turbulent condition) durability. It is believed that this work would profoundly help to identify appropriate nonwetting metallic surfaces based on the intended use environment.

The diploma thesis is focuses on new technology in of high pressure die casting industry. Attention is paid in particular to heating, cooling and the influence of the die lubricants on the quality of castings. theoretical knowledge was applied in practise. The optimization of the production cycle was carried out using a high temperature die lubricant and subsequent evaluation on particular casts in foundry KOVOLIT Modřice a.s.

Ces travaux de thèse portent sur l’élaboration et la caractérisation de revêtements sol-gel composites ≪ CSG ≫ sur acier inoxydable austénitique AISI 304. L’objectif de la thèse était de mettre au point le procédé d'élaboration et d'étudier les propriétés mécaniques et le comportement tribologique des revêtements. La première partie expérimentale présente l’optimisation des conditions de synthèse d’un sol d’alumine stable et l’influence du traitement thermique du gel sur les propriétés physico-chimiques et thermostructurales. Les paramètres étudiés sont : La stabilité chimique du sol et les conditions de traitement thermique (température et temps). Différentes techniques de caractérisations ont été utilisées pour l'optimisation des paramètres d'élaboration (rhéométrie, ATD/ATG, dilatométrie, DRX, MET, pynométrie hélium). Un dopage au nitrate de fer a permis d'améliorer les conditions de frittage de l'alumine sol-gel grâce à la formation d'une solution solide (Al,Fe)2O3. Cela reste cependant insuffisant pour une application du revêtement sur le substrat acier. La seconde partie concerne l’élaboration et la caractérisation mécanique de revêtements sol-gel composites ≪ CSG ≫ charges de particules d’α-Al2O3 et de h-BN. Ce procédé a permis d'obtenir par dip-coating des dépôts monocouches de 8,5 micromètres environ avec des taux de charge de 90% volumique. Cependant, un tel taux de charge provoque la création d’une porosité importante. Les couches CSG traitées thermiquement à 750°C ont par la suite été caractérisées mécaniquement par indentation instrumentée. Les résultats obtenus ont montré une trop faible dureté des couches pour pouvoir améliorer la résistance à l'usure. La dernière partie de la thèse concerne le renforcement des revêtements CSG après traitement à l'acide phosphorique et traitement thermique à 400°C. La formation de liaisons phosphates entre les grains d'alumine renforce l'architecture du composite qui est note CB-CSG ≪ Chemically Bonded Composite Sol-Gel ≫. Des essais d'indentation instrumentée montrent, pour des revêtements CB-CSG charges d’alumine, une amélioration de la dureté par rapport au substrat en acier. Des essais de frottements secs en configuration bille sur plan montrent une augmentation de la résistance aux frottements secs d’un facteur 5 et une diminution du coefficient de frottement par rapport au substrat. L’influence du nitrure de bore hexagonal dans les couches CB-CSG en plus de l'alumine a été étudiée en particulier en ce qui concerne les propriétés mécaniques et tribologiques. / This thesis focuses on the elaboration and the characterization of composite sol-gel coatings “CSG” on austenitic stainless steelAISI 304. The aim of the thesis is to develop the process and to study the mechanical properties and tribological behavior of thecoatings. The first experimental part presents the optimization of the synthesis conditions of a stable alumina sol and the influence of the thermal treatment of the gel on the physic-chemical and thermostructural properties. The studied parameters are: The chemical stability of the sol and the thermal treatment conditions (temperature and time). Various characterization techniques are used in order to optimize the elaboration parameters (rheometry, DTA / TGA, dilatometry, XRD, TEM, helium pycnometry). A Doping with iron nitrate has improved the sintering conditions of the sol-gel alumina through the formation of a solid solution (Al,Fe)2O3. However, this remains insufficient for an application of the coating on the steel substrate. The second part concerns the elaboration and the mechanical characterization of composite sol-gel coatings "CSG" filled with particles of α-Al2O3 and h-BN. This process enables the deposition by dip coating of monolayer coatings of 8.5 micrometers thickness with fill rate of 90% by volume. However, such filler content produces a high porosity. The CSG layers thermally treated at 750°C have been mechanically characterized by instrumented indentation. The results shown to low hardnesses in order to improve the wear resistance. The last part of the work presents the strengthening of CSG coatings with a treatment with phosphoric acid followed by a thermal treatment at 400°C. The formation of phosphate bonds between the alumina grains enhances the architecture of the composite which is denoted CB-CSG "Chemically Bonded Composite Sol-Gel". Instrumented indentation tests show, for CBCSG coatings filled with alumina, an improvement of hardness compared to the steel substrate. Dry friction tests, with ball on disc configuration, show an increase of resistance to dry friction by a factor of 5 and a decrease of the coefficient of friction relatively to the substrate. The influence of the hexagonal boron nitride and of the alumina in the CB-CSG layers on the mechanical and the tribological properties are particularly studied.

Os mecanismos do desgaste e atrito que ocorrem durante o desgaste por deslizamento, bem como, a transição do regime do desgaste moderado para o desgaste severo, são influenciados pela força aplicada, rugosidade, temperatura e umidade, sendo estas variáveis frequentemente estudadas. Entretanto, a avaliação da remoção de debris durante o deslizamento e a influência do aditivo lubrificante, em regime limítrofe/quase seco (e.g. Ácido Esteárico C18H32O2) ainda são necessários maiores entendimentos sobre os mecanismos de desgaste e também a força na qual ocorre a transição do regime do desgaste moderado para o desgaste severo durante o deslizamento. Para os testes a seco, com e sem a remoção dos debris, foram realizados ensaios tribológicos convencionais com as duas durezas de disco, 435 e 530 HV30. Os resultados mostraram que a transição do regime de desgaste é influenciada pela dureza e pela remoção dos debris. A influência da dureza é observada apenas quando os ensaios convencionais são realizados, nos quais foi observado que o aumento da dureza do contra corpo estende a transição do desgaste moderado para o severo em forças maiores. A remoção dos debris aumenta a extensão da força para ocorrer a transição moderado/severo. Para os testes lubrificados, foram realizados ensaios com a dureza de disco de 530 HV, variando a concentração do ácido esteárico. Os resultados mostram que o aumento da concentração do aditivo e da força normal aplicada são varáveis determinantes para a redução do coeficiente de atrito. A ação do aditivo lubrificante é fundamental nas forças baixas, sendo que nas forças elevadas apenas o aumento da força normal é suficiente para manter o baixo coeficiente de atrito. Adicionalmente, para as elevadas forças aplicadas, o filme lubrificante falha em função do tempo de deslizamento, e maiores concentrações de aditivo são necessárias para manter o coeficiente de atrito constante. / The wear and friction mechanisms that occur during the sliding wear, as well as the transition from mild to severe wear regimes are influenced by the normal load applied, roughness, temperature and humidity, the variables more frequently studied. However, the assessment of debris removal during the sliding wear and oil influence with lubricant additive (e.g. Stearic Acid C18H32O2) in the boundary/dry lubrication needs further understanding of the mechanisms and the load that occur a wear transition from mild to severe wear. The aim in this work is the characterization and evaluation the contact surface without debris in sliding surface (cleaning of the wear track) and the wear surface in boundary lubrication tests. The materials studied are: the pin AISI 4140 - 435 HV30 steel and the disc AISI H13 - 435 e 530 HV30 steel. Firstly were made conventional tribological tests with two disc hardness. Then, tests with the cleaning of the wear track were made. The results showed that the hardness and the absence of debris influence in the wear transition regime. The hardness influence is observed only when the conventional tests were made. When the counter body hardness increased, the transition from mild to severe wear extends to greater loads. The debris influence was evidenced in tests with the cleaning of the wear track, and showed that greater loads are needed from mild to severe wear transition. For the lubricated tests, the hardness of the disk was 530 HV. The results shown that the concentration of the lubricant additive and the normal load applied are determinant variables to decreasing the friction coefficient. The lubricant additive action is critical in low loads, and in high loads only the increasing of the load is needed to maintain the low friction. In addition, in the high load applied, the failure of the lubricant film occurs with the increase of the sliding time, and higher additive concentrations are needed to maintain constant the friction coefficient.

Orientador: Elenice Deffune / Resumo: Introdução: A Síndrome do Olho Seco (SOS) é uma doença multifatorial das lágrimas e da superfície ocular que resulta em desconforto, distúrbios visuais e instabilidade do filme lacrimal e afeta principalmente adultos com mais de 50 anos e mulheres. É uma doença que pode ter grande impacto negativo na qualidade de vida dos pacientes. A abordagem terapêutica com soro autólogo tem sido preconizada desde 1986 com prós e contras na literatura. Esta pesquisa teve como objetivo realizar uma revisão sistemática e metanálise para analisar a efetiva contribuição do Soro Autólogo segundo os protocolos, ensaios terapêuticos publicados nos últimos 10 anos e o atendimento dos pacientes portadores de Síndrome do olho seco (SOS) no Hospital das Clínicas da Faculdade de Medicina de Botucatu .Objetivos: 1) realizar revisão sistemática e metanálise para avaliar a eficácia do uso do soro autólogo em comparação com lágrimas artificiais comerciais no tratamento para adultos com olho seco. 2) realizar um trabalho retrospectivo da contribuição do soro autólogo de uso ocular no tratamento da SOS nos pacientes do ambulatório do Hospital das Clínicas de 2014-2018 comparando com o período anterior (2008-2013). Materiais e Métodos: Para a revisão sistemática e metanálise foi pesquisado na base de dados do Pubmed não usando restrições de língua, apenas trabalhos dos últimos 10 anos. Para os desfechos primários e secundários foi utilizado um intervalo de confiança de 95%. O levantamento de dados dos pacien... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Dry Eye Syndrome is a multifactorial disease of tears and ocular surface that results into discomfort, visual disturbances and tear film instability and affects mainly female adults, over 50 years. It is a disease which may cause a great negative impact on the patients’ quality of life. The therapeutic approach employing autologous serum has been advocated in 1986, with pros and cons in the literature. This study aimed to perform a systematic review and a meta-analysis to investigate the effective contribution of Autologus Serum according to the protocols and clinical trials published in the last 10 years, and the SOS patients care at Hospital das Clínicas, during two periods: 2008-2013 and 2014- 2018.Objectives: 1) to perform a systematic review and meta-analysis to evaluate the efficacy of the autologous serum, in comparison to commercial artificial tears for the treatment of dry eye in adults. 2) to carry out a retrospective study of the ocular autologous serum contribution for SOS out patients’ treatment, at Hospital das Clínicas (2014 to 2018), comparing with the previous period (2008-2013).Materials and Methods: For the systematic review and meta-analysis, searches were realized in Pubmed databases, with no language restrictions, for papers published in the last 10 years, with full text availability, for researches dated until 10/12/2018. For the primary and secondary outcomes, a 95% confidence interval was used. For the outpatients’ data collection, each ... (Complete abstract click electronic access below) / Mestre

Lubrificantes são produtos gasosos, líquidos, semi sólidos ou sólidos (pó) que formam um filme entre duas partes evitando o atrito. Lubrificantes de alto desempenho são designados para trabalharem em condições severas de temperatura, pressão e contaminação. Os mais utilizados são os líquidos (óleos) e semi sólidos (graxas). As graxas são aplicadas aonde o óleo pode escorrer e em pontos de difícil acesso e são divididas basicamente em duas classes, sabão e não sabão. A graxa não sabão mais utilizada é a poliuréia, obtida pela reação entre aminas e isocianato, possui elevada tixotropia, alta rigidez dielétrica e excelente poder anticorrosivo, por isso é amplamente utilizada para lubrificação de motores elétricos e maquinário naval. Para obter uma graxa com altíssimo desempenho, nesse estudo foi utilizado o fluido lubrificante sintético polialfaolefina e também foi empregado o aditivo lubrificante sólido politetrafluoroetileno (PTFE) por apresentar o menor coeficiente de atrito conhecido, é comercialmente encontrado irradiado em ar para obter partículas menores e produzir grupos terminais oxigenados que são mais compatíveis com a superfície metálica. Os ensaios foram realizados de forma comparativa usando a graxa de poliuréia pura e aditivada com PTFE. As caracterizações foram feitas por espectroscopia de infravermelho, análise elementar de C, N, e H e índice de NCO livre, comprovando a formação de poliuréia de quatro carbonos (tetrauréia). As propriedades funcionais de ponto de gota e separação de óleo mostraram alta compatibilidade e estabilidade entre os polímeros, que aumentaram quando foi adicionado PTFE. A excelente resistência da graxa de tetrauréia pura ao desgaste e extrema pressão foram demonstradas pelo teste de quatro esferas e teste prático em rolamentos, caracterizando esta graxa como de alto desempenho quando comparada com as graxas mais utilizadas no mercado. / Lubricants are gaseous, liquid, semi solid or solid (powder) materials those form a film between two parties preventing friction. High performance lubricants are designed to work under severe conditions of temperature, pressure, and contamination. The most used are liquids (oils) and semi solids (greases). Greases are applied where oils can drain or in inaccessible places and are divided generally into two classes, soap and no soap. The most used non soap grease is polyurea, obtained by the reaction between amine and isocyanate, has highly thixotropic, high dielectric strength and excellent anticorrosive property, so it is widely used for lubrication of electric motors and shipbuilding machinery. For a grease with high performance, in this study was used a synthetic lubricant fluid, polyalphaolefin, and was also employed solid lubricant additive polytetrafluoroethylene (PTFE) due its lowest coefficient of friction, is found commercially irradiated in air to obtain smaller particles and to produce oxygenated terminal groups those are more compatible with the metal surface. The tests conducted were comparatively between pure polyurea grease and with PTFE additive. The characterizations were made by infrared spectroscopy and elemental analysis of C, N and H and Free NCO index, proving the formation of four carbons polyurea (tetraurea). The functional analysis of drop point and oil separation showed high stability and compatibility between the polymers increased when PTFE was added. The excellent resistance of pure tetraurea grease to wear and extreme pressure were demonstrated by four-ball and practical bearings tests, characterizing this grease as a high performance lubricant, when compared to most used greases in the market.