{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T10:15:39Z","timestamp":1783419339515,"version":"3.54.6"},"reference-count":37,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T00:00:00Z","timestamp":1782950400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"TRBOR Boron Technologies Inc."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>This study investigates the effects of particle size, powder purity, and in situ TiB2 formation on the densification behavior and mechanical properties of B4C-based ceramics fabricated via spark plasma sintering (SPS). The results demonstrate that particle size is the dominant parameter controlling densification and microstructural evolution. An intermediate particle size (F1200) yields the highest relative density (98.41%) and superior mechanical properties, including a hardness of 33.34 GPa and fracture toughness of 4.63 MPa\u00b7m1\/2, by providing an optimal balance between diffusion kinetics and particle packing. The in situ formed TiB2 significantly enhances fracture toughness compared to monolithic B4C. Among the composite samples, the medium particle size containing BT1200 exhibits the best overall combination of properties, with a relative density of 98.00%, hardness of 25.40 GPa, and fracture toughness of 5.18 MPa\u00b7m1\/2. The highest fracture toughness is achieved in the largest particle size containing BT325 (6.29 MPa\u00b7m1\/2), confirming the effectiveness of TiB2 combined with large particle size as a toughening phase. Although higher powder purity contributes to improved phase homogeneity, its influence on densification and mechanical performance is secondary compared to particle size and pore evolution. Excessive particle refinement leads to residual porosity, limiting full densification. Overall, optimizing particle size together with controlled in situ TiB2 formation is essential for achieving high-performance B4C-based ceramics and composites. These findings provide a practical framework for tailoring microstructure and mechanical properties in advanced ultra-hard ceramic systems.<\/jats:p>","DOI":"10.3390\/ma19132820","type":"journal-article","created":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T11:48:32Z","timestamp":1782992912000},"page":"2820","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Densification and Mechanical Properties of Monolithic B4C and In-Situ Formed TiB2 Containing B4C\u2013TiB2: Effects of Particle Size and Impurity"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-3371-0975","authenticated-orcid":false,"given":"\u0130lker","family":"Solako\u011flu","sequence":"first","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, Faculty of Engineering, Marmara University, 34854 Istanbul, T\u00fcrkiye"},{"name":"TRBOR Boron Technologies Inc., 34906 Istanbul, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2015-2186","authenticated-orcid":false,"given":"Furkan","family":"Bulu\u00e7","sequence":"additional","affiliation":[{"name":"Ceramic Research Center, 26005 Eski\u015fehir, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9928-8689","authenticated-orcid":false,"given":"Bahad\u0131r","family":"Tunaboylu","sequence":"additional","affiliation":[{"name":"Department of Metallurgical and Materials Engineering, Faculty of Engineering, Marmara University, 34854 Istanbul, T\u00fcrkiye"},{"name":"Deputy Vice Chancellor Office of Graduate Research, Sultan Qaboos University, Al Khoud, Muscat P.O. Box 17, Oman"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Servet","family":"Turan","sequence":"additional","affiliation":[{"name":"Ceramic Research Center, 26005 Eski\u015fehir, T\u00fcrkiye"},{"name":"Department of Materials Science and Engineering, Faculty of Engineering, Eskisehir Technical University, 26555 Eski\u015fehir, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1080\/0371750X.2013.817755","article-title":"Synthesis, Densification and Characterization of Boron Carbide","volume":"72","author":"Sonber","year":"2013","journal-title":"Trans. Indian Ceram. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/0955-2219(90)90048-K","article-title":"Boron Carbide: A Comprehensive Review","volume":"6","author":"Thevenot","year":"1990","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1016\/S0263-4368(00)00012-3","article-title":"A novel approach for the preparation of B4C-based cermets","volume":"18","author":"Levin","year":"2000","journal-title":"Int. J. Refract. Met. Hard Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2834","DOI":"10.1111\/jace.14295","article-title":"Microstructural Characterization of a Commercial Hot-Pressed Boron Carbide Armor Plate","volume":"99","author":"Xie","year":"2016","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1111\/ijac.12654","article-title":"Densification and characterization of rapid carbothermal synthesized boron carbide","volume":"14","author":"Toksoy","year":"2017","journal-title":"Int. J. Appl. Ceram. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/0022-3115(91)90484-O","article-title":"Boron carbides of various compositions: An improved method for X-rays characterization","volume":"183","author":"Gosset","year":"1991","journal-title":"J. Nucl. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1179\/095066009X12506721665211","article-title":"Synthesis and Consolidation of Boron Carbide: A Review","volume":"55","author":"Suri","year":"2010","journal-title":"Int. Mater. Rev."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Twardowska, A., and Kowalski, M. (2024). The Microstructure, Mechanical, and Friction-Wear Properties of Boron Carbide-Based Composites with TiB2 and SiC Formed In Situ by Reactive Spark Plasma Sintering. Materials, 17.","DOI":"10.3390\/ma17102379"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.ceramint.2005.02.008","article-title":"Pressureless sintering of boron carbide","volume":"32","author":"Roy","year":"2006","journal-title":"Ceram. Int."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"3780","DOI":"10.1111\/jace.15541","article-title":"Synthesis and properties of conductive B4C ceramic composites with TiB2 grain network","volume":"101","author":"Ren","year":"2018","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4911","DOI":"10.1111\/jace.19127","article-title":"B4C\u2013TiB2 composite with modified microstructure and enhanced properties from optimal size coupling of raw powders","volume":"106","author":"Zhao","year":"2023","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3462","DOI":"10.1111\/ijac.14763","article-title":"Toughening mechanism of B4C\/TiB2 ceramic materials by in situ reaction via spark plasma sintering","volume":"21","author":"Du","year":"2024","journal-title":"Int. J. Appl. Ceram. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1023\/A:1026625909365","article-title":"Processing Microstructure, and Mechanical Properties of B4C\u2014TiB2 Particulate Sintered Composites I. Pressureless Sintering and Microstructure Evolution","volume":"39","author":"Skorokhod","year":"2000","journal-title":"Powder Metall. Met. Ceram."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1023\/A:1011378825628","article-title":"Processing, Microstructure, and Mechanical Properties of B4C\u2014TiB2 Particulate Sintered Composites. Part II. Fracture and Mechanical Properties","volume":"39","author":"Skorokhod","year":"2000","journal-title":"Powder Metall. Met. Ceram."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1302","DOI":"10.1016\/j.msea.2010.10.022","article-title":"Microstructure and mechanical properties of pulsed electric current sintered B4C\u2013TiB2 composites","volume":"528","author":"Huang","year":"2011","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"105307","DOI":"10.1016\/j.ijrmhm.2020.105307","article-title":"Microstructure and mechanical properties of B4C-TiB2 composite ceramic fabricated by reactive spark plasma sintering","volume":"92","author":"Wang","year":"2020","journal-title":"Int. J. Refract. Met. Hard Mater."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1016\/j.ceramint.2009.09.004","article-title":"Microstructural characterization of spark plasma sintered boron carbide ceramics","volume":"36","author":"Hayun","year":"2010","journal-title":"Ceram. Int."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1111\/ijac.14492","article-title":"The effect of spark plasma sintering parameters on the densification and mechanical properties of TiB2-TiC-TiB composites","volume":"21","author":"Liu","year":"2024","journal-title":"Int. J. Appl. Ceram. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"116700","DOI":"10.1016\/j.jeurceramsoc.2024.116700","article-title":"Spark plasma sintering of boron carbide (B4C): From characterisation to finite element modeling of sintering","volume":"44","author":"Grippi","year":"2024","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3395","DOI":"10.1016\/j.jeurceramsoc.2009.07.007","article-title":"Static and dynamic mechanical properties of boron carbide processed by spark plasma sintering","volume":"29","author":"Hayun","year":"2009","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2615","DOI":"10.1016\/j.ceramint.2017.10.230","article-title":"Comparisons of the densification, microstructure and mechanical properties of boron carbide sintered by hot pressing and spark plasma sintering","volume":"44","author":"Zhang","year":"2018","journal-title":"Ceram. Int."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1123","DOI":"10.1016\/S0955-2219(02)00274-1","article-title":"High strength B4C\u2013TiB2 composites fabricated by reaction hot-pressing","volume":"23","author":"Yamada","year":"2003","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"26970","DOI":"10.1016\/j.ceramint.2020.07.174","article-title":"Thermodynamical evaluation, microstructural characterization and mechanical properties of B4C\u2013TiB2 nanocomposite produced by in-situ reaction of Nano-TiO","volume":"46","author":"Khajehzadeh","year":"2020","journal-title":"Ceram. Int."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"637","DOI":"10.1016\/j.jeurceramsoc.2010.10.028","article-title":"In situ synthesis and densification of submicrometer-grained B4C\u2013TiB2 composites by pulsed electric current sintering","volume":"31","author":"Huang","year":"2011","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"\u0160vec, P. (2025). Wear Resistance of B4C-TiB2 Ceramic Composite. Lubricants, 13.","DOI":"10.3390\/lubricants13010035"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"329","DOI":"10.2298\/PAC2004329S","article-title":"Reactive sintering of B4C-TiB2 composites from B4C and TiO2 Precursors","volume":"14","year":"2020","journal-title":"Process. Appl. Ceram."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4549","DOI":"10.1016\/j.jeurceramsoc.2024.01.054","article-title":"Low-temperature synthesis and sinterability of high-purity submicron TiB2 powder via microwave-assisted carbothermal reduction","volume":"44","author":"Li","year":"2024","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1023\/A:1006766910536","article-title":"High strength-high toughness B4C-TiB2 composites","volume":"19","author":"Skorokhod","year":"2000","journal-title":"J. Mater. Sci. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4493","DOI":"10.1016\/j.jeurceramsoc.2024.01.080","article-title":"Effects of TiC content on the microstructure and properties of B4C\u2013TiB2\u2013graphite composites by reactive hot pressing","volume":"44","author":"Wang","year":"2024","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_30","unstructured":"(2015). Standard Test Methods for Apparent Porosity, Water Absorption, Apparent Specific Gravity, and Bulk Density of Burned Refractory Brick and Shapes by Boiling Water (Standard No. ASTM C20-00)."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1272","DOI":"10.1016\/j.jeurceramsoc.2021.11.054","article-title":"The effects of in-situ formed phases on the microstructure, mechanical properties and electrical conductivity of spark plasma sintered B4C containing Y2O3","volume":"42","author":"Baskut","year":"2022","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_32","first-page":"175","article-title":"Micro-Mechanical Studies on Pure and Ni Doped ZnS Nanostructured Crystals","volume":"2","author":"Rasool","year":"2010","journal-title":"J. Optoelectron. Biomed. Mater."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1007\/BF00544209","article-title":"Evaluation by indentation of fracture toughness of ceramic materials","volume":"25","author":"Liang","year":"1990","journal-title":"J. Mater. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"117169","DOI":"10.1016\/j.jeurceramsoc.2024.117169","article-title":"The effect of hot forging on the thermal and mechanical properties of spark plasma sintered SiC-TiB2-B4C Composites with CeO2 Addition","volume":"45","author":"Buluc","year":"2025","journal-title":"J. Eur. Ceram. Soc."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Liu, Y., Ge, S., Huang, Y., Huang, Z., and Zhang, D. (2021). Influence of Sintering Process Conditions on Microstructural and Mechanical Properties of Boron Carbide Ceramics Synthesized by Spark Plasma Sintering. Materials, 14.","DOI":"10.3390\/ma14051100"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"15827","DOI":"10.1038\/srep15827","article-title":"Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism","volume":"5","author":"Ji","year":"2015","journal-title":"Sci. Rep."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1521","DOI":"10.1016\/S0955-2219(98)00071-5","article-title":"Processing and mechanical properties of boron carbide sintered with TiC","volume":"18","author":"Sigl","year":"1998","journal-title":"J. Eur. Ceram. Soc."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/13\/2820\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T09:39:17Z","timestamp":1783417157000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/13\/2820"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,2]]},"references-count":37,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["ma19132820"],"URL":"https:\/\/doi.org\/10.3390\/ma19132820","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,2]]}}}