Andrea Spitzer

Bio: Andrea Spitzer is an academic researcher from Bundesanstalt für Materialforschung und -prüfung. The author has contributed to research in topics: Sintering & Ceramic. The author has an hindex of 4, co-authored 20 publications receiving 33 citations.

Characterization of powder flow behavior for additive manufacturing

Abstract: The flow behavior of powders has an essential role in many industrial processes, including powder bed additive manufacturing. The characterization of the flow behavior is challenging, as different methods are available, and their suitability for an application in additive manufacturing is still controversial. In this study, six standardized methods (measurement of bulk density by ISO 60 and by ASTM B329, angle of repose by ISO 4324, discharge time by ISO 6186 and by ASTM B964–16, and Hausner Ratio by ASTM 7481–18), the rotating drum method (by GranuDrum) and powder rheometry (Anton Paar powder cell), were applied to five size fractions of a crushed quartz sand powder and compared. A statistical approach is proposed and discussed to correlate the obtained flowability indexes with the packing density of powder beds deposited layer-by-layer, and these correlations are compared between methods. Overall, the measurement of bulk density by ASTM B329 showed the best correlation with the powder bed density. Advanced methods such as the rotating drum method and powder rheometry did not demonstrate particularly good correlations, however they provided complementary information which can be useful to assess the dynamic behavior of powders.

Searching for biological feedstock material: 3D printing of wood particles from house borer and drywood termite frass.

Abstract: Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer (EHB) and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the EHB Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of wood-based structures in a layer wise fashion using the Binder Jetting printing process. The quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a Hausner Ratio HR = 1.1 with ρBulk = 0.67 g/cm3 and ρTap = 0.74 g/cm3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing.

Biocompatible sheet material containing calcium phosphate, and method for making it

Abstract: The invention relates to a sheet material which contains calcium phosphate and which is compatible with a biological medium. It consists of a main body which contains, as main constituent, calcium orthophosphate and on which there is situated at least one outer sheet releasing calcium ions, the release of calcium from the sheet being greater than the release of calcium from the main body. The sheet material, which can be used as a temporary or permanent bone replacement substance, is produced by treatment with an acid or application of a sheet containing calcium compounds and subsequent heating between 400 and 1000 DEG C.

Bone replacement material with orthophosphate

Abstract: The present invention relates to a material with orthophosphate and having a high solubility which can be used as a bioactive bone replacement material and as a substrate material in biotechnology. According to 31 P-NMR measurements, the new material comprises Q 0 -groups of orthophosphate and Q 1 -groups of diphosphate, the ortho-phosphates or Q 0 -groups making up 65 to 99.9% by weight relative to the total phosphorus content of the finished material and the diphosphates or Q 1 -groups making up 0.1 to 35% by weight relative to the total phosphorus content of the finished material, and wherein according to X-ray diffractometric measurements and relative to the total weight of the finished material, 35 to 99.9% by weight of a main crystal phase consisting of Ca 10 Na(PO 4 ) 7 , Ca 10 K(PO 4 ) 7 , mixtures thereof or mixed crystals according to the general formula Ca 10 K x Na 1−x (PO 4 ) 7 , where x=0 to 1, is contained in the bone replacement material and 0.1 to 25% by weight of a substance selected from the group consisting of Na 2 CaP 2 O 7 , K 2 CaP 2 O 7 , Ca 2 P 2 O 7 and mixtures thereof is contained as a secondary crystal phase, and the X-ray amorphous phases contained besides the main crystal phase jointly make up 0.1 to 65% by weight.

Searching for biological feedstock material: 3D printing of wood particles from house borer and drywood termite frass

Abstract: Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the European house borer (EHB) Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of wood-based structures in a layer wise fashion using the Binder Jetting printing process. The quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a HR = 1.1 with ρBulk = 0.67 g.cm -3 and ρTap = 0.74 g.cm -3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing.

A review on wood powders in 3D printing: processes, properties and potential applications

Abstract: Three-dimensional (3D) printing is a technology that, for a multitude of raw materials, can be used in the production of complex structures. Many of the materials that currently dominate 3D printing (e.g. titanium, steel, plastics, and concrete) have issues with high costs and environmental sustainability. Wood powder is a widely available and renewable lignocellulosic material that, when used as a fibre component, can reduce the cost of 3D printed products. Wood powder in combination with synthetic or natural binders has potential for producing a wide variety of products and for prototyping. The use of natural binders along with wood powder can then enable more sustainable 3D printed products. However, 3D printing is an emerging technology in many applications and more research is needed. This review aims to provide insight into wood powder as a component in 3D printing, properties of resulting products, and the potential for future applications.

Biodegradable composite material

Abstract: The invention relates to a biodegradable composite material and to a method for producing same. The biodegradable composite material according to the invention is preferably a bone-building material that can be used in the field of regenerative medicine, particularly as a temporary bone defect filler for bone regeneration.

CaO-MgO-SiO2-based bioactive glass and sintered calcium phosphate glass using same

Abstract: A bioactive glass having a composition substantially comprising 20 to 40 mol % of CaO, 40 to 60 mol % of SiO 2 , and 10 to 20 mol % of MgO is high in bioactivity and mechanical strength, and a sintered calcium phosphate glass using the bioactive glass as a sintering aid is excellent in biocompatibility and mechanical strength.

Bioactive rhenanite glass ceramic

Abstract: Bioactive glass ceramic (A) comprises a crystalline phase containing rhenanite (I) and a glass phase. (A) comprises, by weight, 29.5-70% silica; 5.5-23% calcium oxide; 6-27.5% sodium oxide; 2-23.5% phosphorus pentoxide and 0-1.5% fluoride, and is essentially free of alumina. Independent claims are also included for: (1) preparing (A); (2) shaped articles that contain, or comprise, (A); and (3) bioactive composite consisting of (A) and an organic compound. ACTIVITY : Osteopathic. No details of osteopathic activity are given. MECHANISM OF ACTION : Induction of apatite formation.

Use of Wood in Additive Manufacturing: Review and Future Prospects

Abstract: Polymers filled with natural-based fillers have shown growing demand/interest in recent years, including in additive manufacturing. Like most natural fillers in 3D printing, wood particles serve mainly as a filler that lowers the cost of the printing material due to their low price. However, could wood be used as a main ingredient to affect/improve the properties of 3D-printed parts? Several advantages, such as its reinforcing ability, biodegradability, availability as waste material from other industries, ability to be used in different forms or only in partial components, recycling options or even the use of its undesirable hydromorph-induced dimensional instability for 4D printing, indicate the importance of exploring its use in 3D printing. A review of publications on 3D printing with wood biomass and technologies involving the use of wood particles and components was conducted to identify the possibilities of using wood in additive technologies and their potential.