3D printing by selective laser sintering (SLS) of high-dose drug delivery systems using pure brittle crystalline active pharmaceutical ingredients (API) is possible but impractical. Currently used pharmaceutical grade excipients, including polymers, are primarily designed for powder compression, ensuring good mechanical properties. Using these excipients for SLS usually leads to poor mechanical properties of printed tablets (printlets). Composite printlets consisting of sintered carbon-stained polyamide (PA12) and metronidazole (Met) were manufactured by SLS to overcome the issue. The printlets were characterized using DSC and IR spectroscopy together with an assessment of mechanical properties. Functional properties of the printlets, i.e., drug release in USP3 and USP4 apparatus together with flotation assessment, were evaluated. The printlets contained 80 to 90% of Met (therapeutic dose ca. 600 mg), had hardness above 40 N (comparable with compressed tablets) and were of good quality with internal porous structure, which assured flotation. The thermal stability of the composite material and the identity of its constituents were confirmed. Elastic PA12 mesh maintained the shape and structure of the printlets during drug dissolution and flotation. Laser speed and the addition of an osmotic agent in low content influenced drug release virtually not changing composition of the printlet; time to release 80% of Met varied from 0.5 to 5 h. Composite printlets consisting of elastic insoluble PA12 mesh filled with high content of crystalline Met were manufactured by 3D SLS printing. Dissolution modification by the addition of an osmotic agent was demonstrated. The study shows the need to define the requirements for excipients dedicated to 3D printing and to search for appropriate materials for this purpose.

As part of the tests, a two-phase NiAl/Ni₃Al alloy and a composite based on this alloy with 4 vol% addition of TiB₂ were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB₂ composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress–strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB₂ ceramic particles uniformly distributed on grain boundaries.

The microstructure, mechanical properties, and friction-wear performance of (TiB_x/TiSi_yC_z)x3 multilayer coatings deposited on the M2 steel by the pulsed laser deposition are investigated in detail in as-deposited state and after annealing at 500 °C for 5 min in air. Scanning and transmission electron microscopies are used to reveal microstructural changes caused by annealing. The influence of post-deposition annealing on hardness and Young modulus is studied in nanoindentation test. A scratch-test is applied to reveal changes in adhesion and the coefficient of friction (CoF) of coated samples with diamond before and after annealing. Friction-wear properties are also analyzed in dry sliding with Al₂O₃ and 100Cr6 steel in ball-on-disc tests. Our analysis shows that the post-deposition annealing leads to partial devitrification of the TiB_x layers, where nanocrystalline TiB₂ phase is identified, while the TiSi_yC_z layers retain amorphous. Annealing significantly increases mechanical properties of coated samples and adhesion of the (TiB_x/TiSi_yC_z)x3 multilayer to steel substrates. Friction-wear properties of coated samples are also notably improved. The values of CoF for coated samples tested with diamond (in the scratch-test), alumina, and 100Cr6 steel (ball-on-disc tests) are in the range of 0.05–0.23, while for M2 steel the CoF values are 0.8, 0.45, and 0.8, respectively.