Selection Of Metallic Materials Research Articles

(Digital Presentation) Electrochemical Corrosion Evaluation of Metallic Materials in Hahm Pyrolysis Bio-Oil

Biomass-derived pyrolysis oils contain organic acids, water and oxygenates that can degrade metallic materials with low corrosion resistance. To construct storage tanks for such bio-oils, the selection of metallic materials with sufficient corrosion compatibility is of high importance. This work evaluated corrosion compatibility of Cr-alloyed steels and stainless steels in a pyrolysis bio-oil using electrochemical impedance spectroscopy (EIS). High-Ash High-Moisture (HAHM) bio-oil, produced from a forest residue feedstock by National Renewable Energy Laboratory in Golden, CO, was used as the test liquid for EIS measurements. The corrosion reaction resistance, determined from the impedance data, indicated that stainless steels with the critical value of Cr or Cr + Mo content exhibit corrosion resistance in the bio-oil. In post-exposure optical inspection, no change was found for the specimens with high corrosion reaction resistance while visually changed surfaces were observed from the specimens with low corrosion reaction resistance.

A practical model for efficient anti-fatigue design and selection of metallic materials: II. Parameter analysis and fatigue strength improvement

In the first paper, a Y-T-F model was proposed based on the restrictions of both strength and plasticity; the corresponding applications on the fatigue strength prediction have also been discussed. In this second paper, the emphasis will be put on the issues of fatigue strength improvement. Based on the primary form of the Y-T-F model, the parameters are further analyzed and quantified, to clarify the influences of various factors on fatigue strength. Firstly, the damage capacity C is proved to be sensitive to the elastic modulus E, which could change with the alloying components and nano-scaled grain boundaries; the increase of E would lead to the increasing C, thus increase the fatigue strength. Secondly, the microstructure characteristic coefficient a, as well as the yield strength σy and tensile strength σb in the crack initiation region could be influenced by the processing mode, grain size and microstructure uniformity of materials; the change of microstructure characteristics would affect the changing tendency of tensile strength--fatigue strength relation via varying the values of a, σy and σb. Thirdly, the damage weight coefficient ω is found to be a reflection of the fatigue strength declination induced by defects; the defect dimension D, the defect shape correlated stress concentration coefficient Kt, as well as the strengthening level of matrix materials σb are all corresponding factors. Quantified correlations between the above parameters and corresponding factors are comprehensively built up, hence obtaining the influences of either a single factor or multiple factors on fatigue strength. This further developed Y-T-F model would be helpful to clarify the direction of fatigue strength improvement, and contribute to the anti-fatigue design optimization of metallic materials.

A practical model for efficient anti-fatigue design and selection of metallic materials: I. Model building and fatigue strength prediction

The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic materials. For this problem, a theoretical fatigue model is proposed in this study, the possible applications have also been discussed. Specific results would be introduced in two serial papers, in which the first paper focuses on the model building and the applications on fatigue strength prediction; the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength improvement. In this first paper, a theoretical model is proposed considering both the strength and plastic restrictions of fatigue strength. As the model builds up a brief relationship among yield strength (Y), tensile strength (T) and fatigue strength (F), it is named as the Y-T-F model. Through the verification with fatigue strength data covering various kinds of metallic materials and loading conditions, this Y-T-F model exhibits both generality and accuracy. With the Y-T-F model, the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation, just through yield strength, tensile strength and several known fatigue strength data. Moreover, through its deduced Y-F model, the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained, as well as the maximum value of fatigue strength and corresponding critical yield strength. In summary, the Y-T-F model would be useful for reducing the fatigue tests, thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.

Gigi Tiruan Sebagian Kerangka Logam sebagai Penunjang Kesehatan Jaringan Periodontal

Penggunaan gigi tiruan sebagian sangat penting dalam mempertahankan kesehatan jaringan periodontal dan menjaga stabilitas gigi yang tersisa. Pembuatan gigi tiruan yang tepat merupakan fase integral dari perawatan penyakit periodontal secara keseluruhan dalam mempertahankan kesehatan jaringan periodontal tersebut.Gigi tiruan sebagian lepasan harus didesain untuk dapat mengurangi penumpukan sisa makanan serta plak pada gigi dan tepi gingiva dari gigi penyangga. Pemilihan bahan logam sebagai gigi tiruan pada kasus periodontal kompromis dapat membantu dalam mencegah pergerakan gigi dan mempertahankan posisi gigi pasca perawatan periodontal karena sifat logam yang lebih kaku dibandingkan dengan bahan lainnya, sehingga keberhasilan perawatan dapat tercapai. Pembuatan gigi tiruan kerangka logam yang baik dan kerjasama yang baik antara semua anggota tim medis dalam menangani kasus akan menghasilkan keberhasilan perawatan yang dilakukan. Tujuan dari penulisan sari pustaka ini adalah menambah ilmu dan wawasan periodontis dan prostodontis dalam penggunaan gigi tiruan sebagian lepasan kerangka logam pasien periodontal kompromis. Pemberian informasi dan mendidik pasien dalam menjaga kebersihan gigi tiruan dan mulutnya juga merupakan faktor penting yang menentukan keberhasilan pembuatan gigi tiruan.Frame Partial Denture as a Supportive Therapy for Periodontal Health. Partial denture is very important in maintaining periodontal health and maintaining the stability of the remaining teeth. The fabrication of denture is an important phase in comprehensive periodontal health therapy, so as to maintain the periodontal health. Removable partial dentures should be designed to reduce the accumulation of food residue and plaque on the teeth and gingival edge of the abutment. The selection of metallic materials as denture in case of periodontal compromise can help in preventing tooth movement and maintain the position of the teeth after periodontal treatment because the nature of metal is more rigid when compared with other materials, so that the success of the treatment can be achieved. Making good metal framework denture and good cooperation between all members of the medical team in handling the case will result in a successful treatment. The aim of the study is to enrich the knowledge for periodontists and prosthodontists in using metal removable prothesis in compromised periodontal patients. Providing information and educating patients in maintaining the cleanliness of denture and mouth are also an important factor that determines the success of the manufacture of dentures.

<i>In Vitro</i> Corrosion Behaviour of Metallic Dental Materials

Typical applications of metallic dental materials include metal-ceramic restorations, dental implants or orthodontic systems. Due to their contact with human tissues, corrosion resistance is one of the main requirements for dental materials. In the present paper, the corrosion behaviour in Fusayama Meyer artificial saliva solution (pH=5.2) on a selection of four different metallic dental materials (316 L steel, Au based alloy, cp-Ti, Ti6Al4V alloy) currently used in dentistry were investigated. The metallic dental materials have been investigated in terms of electrochemical analysis, chemical composition, morphology before and after corrosion, wettability and roughness. The results showed a hydrophilic behaviour in the case of Au based alloy, cp-Ti and Ti6Al4V alloy, and hydrophobic for 316L stainless steel. Considering the main electrochemical parameters, the cp-Ti alloy exhibited better corrosion resistance in artificial saliva with pH=5.2, followed by Au based alloy, Ti6Al4V alloy and 316L stainless steel. The main objective of the present paper was to evaluate the corrosion behaviour, as in important factor in the selection of metallic materials used in dentistry.

C–HAp composite layers deposited onto AISI 316L austenitic steel

Despite significant progress made in the selection of metallic materials used in various types of medical implants, their toxic effects on the human body have yet to be entirely eliminated. This is especially important in the case of metallic materials used in long-term medical implants. Hydroxyapatite and carbon coatings appear to be particularly interesting in this field. Surface engineering techniques can be applied to obtain a major improvement of biocompatibility, corrosion and wear resistance of metallic biomaterials without losing their beneficial mechanical properties. Carbon coatings were synthesized using RF PACVD method, whereas HAp layers were subsequently deposited by PLD technology. Morphology and chemical composition of composite layers were determined using SEM. X-ray diffraction was applied for phase composition investigation. Potentiostatic and potentiodynamic characteristics in Tyrode's solution allowed to determine the corrosion features of C–HAp layers. Adhesion of synthesized coatings was determined using nanoindentation technique. Results obtained in the present investigation prove the good influence of carbon interlayer on adhesion of HAp coatings, however the corrosion feature investigation gave ambiguous results. Carbon interlayer has been found to noticeably improve the corrosion features of AISI 316L alloy, however subsequent deposition of HAp layer resulted in decreased corrosion parameters, which can be an effect of applied PLD deposition technique.

Advanced testing methods for studying the mechanical behavior of materials

This article considers some problems associated with the selection of metallic materials used in engineering structures and environments. A common dilemma in engineering is the proliferation of newly designed (mostly high-strength and/or corrosion-resistant) steels and alloys that are unusable in industry as they are highly susceptible to failure under operating conditions including environmentally assisted cracking. The problem of materials failure has several sources, the most significant of which is how engineers select which material to use in which industry.

The implementation of tribological principles in an expert-system ("PRECEPT") for the selection of metallic materials, surface treatments and coatings in engineering design

The implementation of tribological principles in an expert-system ("PRECEPT") for the selection of metallic materials, surface treatments and coatings in engineering design

Intraoral corrosion resulting from coupling dental implants and restorative metallic systems.

Materials used for the construction of dental restorations and implants include a wide range of metals and alloys, ceramics and carbons, and polymers. When metals and alloys are placed in direct contact in the oral cavity, a galvanic cell can be formed that may compromise the longevity of one or more of the materials in the couple. In vitro electrochemical corrosion analyses have proven to be a valuable tool for providing guidance on the selection of metallic materials. These analyses can provide basic data on electrochemical potentials, current rates, and the evaluation of galvanic corrosion conditions. This article seeks to provide the clinician with information that can be valuable in the selection of metallic materials that may be placed in direct contact with one another in the oral cavity.