Boron Powder Research Articles

Effect of Astroloy powder characteristics on mechanical properties of Powder-HIP components

Astroloy, Ni-based superalloy, with a high-volume fraction of γ', is beneficial for high temperature applications but, at the same time, has limited forgeability. For this reason, powder metallurgy (PM) is the only viable processing route for this alloy. In particular, Near Net Shape powder-HIPping (NNSHIP) is attracting much interest since it offers a possible solution to the high cost of PM production by reducing the amount of post-process forging and machining steps. However, this method still has some issues to overcome, such as the presence of prior particle boundaries (PPBs) decorated with carbides and/or oxides, which drastically reduce the material's mechanical properties. Many studies have attempted to solve this issue by optimizing HIP cycles and heat treatments (HTs), although powder characteristics, more specifically interstitial content, affect PPB presence and mechanical properties of HIP + HTed material. Additionally, powder boron content can have a major effect on material microstructure and mechanical properties. In this work, four powders with different particle size distribution (PSD), oxygen, carbon and boron content were studied. In doing so, the four powder batches and their HIP + HTed samples were fully characterized in terms of chemical composition, grain size and γ' system, and these properties were linked to the mechanical properties of the samples in order to define optimized powder characteristics. The optimized powder demonstrated more than 23 vol % of tertiary γ' due to a high boron content (259 ppm), a carbon content below 160 ppm, and an oxygen content below 150 ppm. With these characteristics, HIP + HTed Astroloy component obtained an improvement, with respect to the aeronautical AMS 5852B standard, of 7 % in ultimate tensile strength (UTS), 3 % in yield strength (YS), 84 % in elongation, 29 % in impact toughness and 22 % in hardness at room temperature. Additionally, at high temperatures, 760 °C, values are around the standard demands with an increase of 2 % in YS and a decrease of 7 % in UTS and 28 % in elongation, being the last one the best result obtained among the tested powders; also impact toughness at 760 °C presents a value close to room temperature requirements with 30 J.

Combustion performance of aluminum modified boron nanoparticles coated with silane coupling agent

Boron (B) powder, with its high mass and volumetric heat values, makes it highly promising in the field of energetic materials. However, the oxide layer on the B surface is the most significant barrier to realizing its full potential as a fuel. How to eliminate or disrupt the oxide layer is currently an urgent problem that needs to be addressed. This study proposes an approach to enhance the combustion of nano-B powder by coating aluminum (Al) onto its surface using a silane coupling agent. The combustion characteristics of Al-modified B powder with different Al contents were investigated through experimental and molecular dynamic simulation methods, and the bidirectional diffusion mechanism on the interfacial layer of modified B particles was revealed. A small amount of Al powder can largely lower the initial oxidation temperature of B powder, increase the maximum flame temperature, and enhance the heat release. However, an excessive amount of Al powder leads to a deterioration in the combustion of B powder but can alter the combustion behavior and suppress the aggregation of B powder during the combustion. Additionally, combination reaction and redox reaction occurring during the combustion of B@Al samples not only reduce the burning time of B powder but also accelerate the flame expansion speed and improve the combustion efficiency. These results lay the foundation for the application of B@Al in the field of energetic materials.

Defect-regulated synthesis of ZrB2 powders via carbon thermal reduction and elucidation of its hot-pressing densification mechanism

Through defect modulation, ZrB2 powder was controllably synthesized using the carbon thermal reduction (CTR) method, with boron powder serving as a novel additive. Thermodynamic data for the ZrO2-B2O3-C system in the presence of boron were calculated using HSC thermodynamic software. Additionally, TG-DSC thermal analysis combined with XRD was used to investigate the reaction process. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to analyze the defect structure and grain surface characteristics of the reaction products. The results indicate that the reaction of B with ZrO2 and C exothermically alters the nucleation environment of ZrB2 grains. The helical dislocations generated act as a source of crystal growth steps, promoting the growth of smooth interfaces and leading to a transformation of the ZrB2 grain growth mechanism. Quantitative calculations of the dislocation density of ZrB2 powders, using the convolutional multiple whole profile fitting (CMWP-fit), suggest that the inclusion of boron as an additive can modulate the defect concentration of the products. ZrB2 powders with varied dislocation densities were achieved through meticulously controlled synthesis methods, followed by subsequent densification via hot pressing sintering. The results indicated that the relative density of ZrB2 ceramics increased from 83.9 % to 96.7 % as the dislocation density of the powder increased from 2.7 × 1013 m−2 to 7.6 × 1014 m−2 with the rise in boron content from 0 wt% to 3 wt%. In addition, the defects create extra sintering-driving forces that induce a shift in the densification mechanism from grain boundary diffusion to dislocation slip during hot-pressing sintering. This shift results in an increase in the apparent activation energy from 105 kJ/mol to 210 kJ/mol.

Effects of nano-metal oxide additives on ignition and combustion properties of MICs-boron rich fuels

Boron has been considered a promising powdered metal fuel for enhancing composite propellants' energy output due to its high energy density. However, the high ignition temperature and low combustion efficiency limit the application of boron powder due to the high boiling point of the boron oxide layer. Much research is ongoing to overcome these shortcomings, and one potential approach is to introduce a small quantity of metal oxide additives to promote the reaction of boron. This study prepared boron-rich fuels with 10 wt% of eight nano-metal oxide additives by mechanical ball milling. The effect of metal oxides on the thermo-oxidation, ignition, and combustion properties of boron powder was comprehensively studied by the thermogravimetric analysis (TG), the electrically heated filament setup (T-jump), and the laser-induced combustion experiments. TG experiments at 5 K/min found that Bi2O3, MoO3, TiO2, Fe2O3, and CuO can promote thermo-oxidation of boron. Compared to pure boron, Tonset can be reduced from 569 °C to a minimum of 449 °C (B/Bi2O3). Infrared temperature measurement in T-jump tests showed that when heated by an electric heating wire at rates from 1000 K/s to 25000 K/s, the ignition temperatures of B/Bi2O3 are the lowest, even lower than the melting point of boron oxide. Ignition images and SEM for the products further showed that the high heating rate is beneficial to the rapid reaction of boron powder in the single-particle combustion state. Fuels (B/Bi2O3, B/MoO3, and B/CuO) were mixed with the oxidant AP and ignited by laser to study the combustion performance. The results showed that B/CuO/AP has the largest flame area, the highest BO2 characteristic spectral intensity, and the largest burn rate for powder lines. To combine the advantages of CuO and Bi2O3, binary metal oxide (CBO, mass ratio of 3:1) was prepared and the test results showed that CBO can very well improve both ignition and combustion properties of boron. Especially B/CBO/AP has the highest burn rate compared with all fuels containing other additives. It was found that multi-component metal-oxide additive can more synergistically improve the reaction characteristics of boron powder than unary additive. These findings contribute to the development of boron-rich fuels and their application in propellants.

Effects of Porosity and Boron Reinforcement in AISI 316L Stainless Steel for Biomedical Applications

AISI 316L stainless steel (SS) is one of the most widely used biomaterials in the manufacture of implants and biomaterials. It has advantages over equivalent biomaterials such as low cost, good mechanical properties and biocompatibility. The pores found in porous biomaterials provide mechanical interlock, ensuring strong attachment of the implant to the tissue. In this study, 20%, 30% and 40% by volume of polyvinyl alcohol (PVA) and Boron powder were added into 316L powder to obtain porous SS implant. To investigate the effect of porosity and boron effect on the stainless-steel implant material, the samples produced in PVA and Boron added groups, were sintered at 1180 oC under an argon atmosphere. With the evaporation of PVA in the structure, porous and boron added samples were obtained in two groups. Finally, the samples were subjected to Brinell hardness and compression tests and analyzed by SEM, EDS and XRD. As a result of the hardness tests, the highest values were measured as 37.006, 31.32, 25.28 HB. 39.5, 34.5, 26.2 MPa strengths were measured for 20%, 30% and 40% porous samples respectively.

Preparation and properties of nano B/NC/AP@F2602 double-layer energetic fiber

The nano-boron powder (n-B) exhibits remarkable efficacy as a combustion catalyst, making it a prime candidate for use in solid propellant metal burners. Nevertheless, throughout the storage phase, the surface of n-B powder is prone to oxidation and substantial agglomeration, resulting in challenges with ignition and incomplete energy dissipation when utilizing boron powder. In this study, we utilized the coaxial electrospinning technique to produce nanofibers comprised of nano-boron /nitrocellulose/ammonium perchlorate@fluororubber (n-B/NC/AP@F2602), with the nano boron uniformly distributed within the core-shell fibers. In the course of combustion, the fibrous composite of n-B/NC/AP@F2602 undergoes an escalation in the rates of energy output and energy release, owing to the constraints imposed by external F2602((C₂H₂F₂)n and (C₃F₆)n). The n-B/NC/AP@F2602 demonstrates a 1.4-fold increase in peak pressure and a 3.6-fold increase in maximum boost rate when compared to the n-B/NC/AP. The energy performance evaluation results reveal that the mean molecular weight (MC) of combusted products from n-B/NC/AP@F2602 is 29.2 g·mol−1, representing a substantial increase compared to that of n-B/NC/AP. The aforementioned findings exemplify that coaxial electrospinning is an exceedingly efficacious technique for enhancing nanostructures, thereby amplifying the reactivity of energetic particles and offering novel insights into their application in energetic materials.

Stability analysis of WEST L-mode discharges with improved confinement from boron powder injection

WEST L-mode plasmas with dominant electron heating and no core torque source have observed improvements in confinement during boron (B) powder injection. These results are reminiscent of previous powder injection experiments on other devices and gaseous impurity seeding experiments on WEST. During powder injection, the stored energy increased up to 25% due to enhanced ion and electron heat and particle confinement. The improvements in confinement were not indicative of an L-H transition. To identify the dominant mechanisms and the causality chain behind these improvements in confinement, we employ interpretative modeling using METIS, predictive integrated modeling using a high-fidelity plasma simulator (HFPS), and stand-alone gyrokinetic simulations using quasi-linear gyrokinetic code. Interpretative modeling with METIS allowed for the estimation of missing data while maintaining good overall consistency with experiment. These results provided the initial conditions for fully predictive flux driven simulations using the HFPS. From these simulations, quasi-linear gyrokinetic analysis was performed at ρ=0.5 and ρ=0.65 . Collisionality was found to be a strong candidate for the turbulence suppression mechanism at ρ=0.5 , while a combination of collisionality and the Te/Ti ratio was found to be the likely mechanism at ρ=0.65 . The results additionally suggested that increased Zeff (through main ion dilution) could play a role in the improved confinement, but this could not be confirmed due to a lack of experimental measurements. The modeling framework established here can now be used to evaluate and exploit a variety of future powder injection experiments.

Synthesis of high entropy monoboride (Mo0.25W0.25Cr0.25Ta0.25)B powders with abundant twins from oxides

AbstractHigh entropy monoborides powders are mainly prepared from metal and boron powders which can be costly. In this study, a novel approach starting from mixed oxides, boron carbide, and graphite was first developed to synthesize quaternary monoboride powders by combining multiple boro/carbothermal reductions (MBCTR). As an exemplar, (Mo0.25W0.25Cr0.25Ta0.25)B powders with purity up to 94.3 wt.% were successfully synthesized by heating the mixtures in vacuum at 1650°C for three times, as‐synthesized powders exhibit fine particle size (<1 µm) and uniform elemental distribution. MBCTR not only increased the purity of monoborides but resulted in abundant twins and stacking faults in the final powders. This work has proposed a new and low‐cost strategy of synthesizing high‐purity and fine monoboride powders.

Investigation of the effect of impurity of precursor materials on Si‐doped boron carbide properties

AbstractBoron carbide is a notable ceramic, with its high hardness and low density. However, it suffers a sudden loss in strength under high shear stress. Doping boron carbide with Si/B is widely used to increase its resistance to amorphization. High purity boron and silicon hexaboride precursor powders are used for doping boron carbide, but these materials have high costs and supply chain constraints. This research investigated the effect of substituting lower purity B or using pure Si powder instead of SiB6 on materials’ properties such as elastic and mechanical properties, microstructure, and amorphization resistances. It was observed that using lower‐purity boron or pure Si powder instead of SiB6 did not significantly affect critical properties, such as fracture toughness, hardness, or amorphization resistance. However, Young's modulus values decreased as B purity decreased and as Si was used instead of SiB6. These findings demonstrate that substituting precursor materials in Si/B co‐doped B4C is possible with little change in the material's properties. This facilitates the use of easier‐to‐access, cheaper production routes to be used for silicon‐doped boron carbide products.

Mechanochemical synthesis, purification, and optimization studies of Cr boride@MgO particles

Chromium boride, an advanced ceramic material, is commonly produced by powder metallurgy methods using elemental boron and chromium powder, borothermic reactions, or boron carbide reduction of Cr2O3. In this study, a mechanochemical method for the production of chromium boride was developed, subsequent purification was performed, and the whole process was optimized. The amounts of Cr2O3, B2O3, and Mg in the initial powder blends were determined by computational thermodynamic methods based on their equilibrium compositions. Firstly, stoichiometric starting-powder blends were milled at different durations (1, 2, 3, 4, 5, and 8 h). The optimum purification route was determined using acid leaching experiments carried out with different acids, at different temperatures, and concentrations. Secondly, powders prepared in excess amounts were synthesized at the optimum duration (5 h) and leaching condition (0.1 M HCl, 25 °C). For the 100 wt % excess B2O3, 25 wt % excess Mg and 0.8 moles of Cr2O3 composition, annealing was conducted at 1100 °C. Characterization studies, X-ray diffractometry (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and atomic absorption spectroscopy (AAS) were conducted on the milled and leached powders. After annealing, CrB, CrB2, Cr3B4 and MgO phases were obtained in the XRD patterns. The particle sizes of the resulting materials were also analyzed, and it was found to be nearly 3.11 μm after annealing. Finally, the TEM analysis revealed that the MgO peak evident in the XRD patterns was MgO shell covering the Cr boride particles having submicron sizes; hence, a pure Cr boride@MgO core-shell structure was obtained.

Enhanced Fe(ii)/Fe(iii) cycle by boron enabled efficient Cr(vi) removal with microscale zero-valent iron.

Recently, researchers have been paying much attention to zero-valent iron (ZVI) in the field of pollution remediation. However, the depressed electron transport from the iron reservoir to the iron oxide shell limited the wide application of ZVI. This study was aimed at promoting the performance of microscale ZVI (mZVI) for hexavalent chromium (Cr(vi)) removal by accelerating iron cycle with the addition of boron powder. It was found that the addition of boron powder enhanced the Cr(vi) removal rate by 2.1 times, and the proportion of Cr(iii) generation after Cr(vi) removal process also increased, suggesting that boron could promote the reduction pathway of Cr(vi) to Cr(iii). By further comparing the Cr(vi) removal percentage of Fe(iii) with or without the boron powder, we found that boron powder could promote the percentage removal of Cr(vi) with Fe(iii) from 10.1% to 33.6%. Moreover, the presence of boron powder could decrease the potential gap values (ΔEp) between Fe(iii) reduction and Fe(ii) oxidation from 0.668 V to 0.556 V, further indicating that the added boron powder could act as an electron sacrificial agent to promote the reduction process of Fe(iii) to Fe(ii), and thus enhancing the reduction of Cr(vi) with Fe(ii). This study shed light on the promoted mechanism of Cr(vi) removal with boron powder and provided an environmentally friendly and efficient approach to enhance the reactivity of the mZVI powder, which would benefit the wide application of mZVI technology in the environmental remediation field.

EFFECTS OF FLUORINATED AND NON-FLUORINATED ADDITIVES ON BURNING RATES OF BORON-TEFLON BLENDS FOR SOLID ROCKET PROPULSION

Boron is considered a promising metal fuel for energetic propellants due to its high energy density, but in practice, boron experiences slow combustion kinetics. Fluorinated additives can improve boron combustion. The objective of this study was to determine how different fluorinated additives would affect the burn rate of a boron-based fuel in a high-pressure inert environment. Boron powder was sintered with polytetrafluoroethylene (PTFE) powder to create test pellets with variable fluorine:boron mass ratios. Three different purities of boron powders were tested, along with three different fluoropolymer additives and 14 other additives, which varied in molecular morphology and fluorination. The base boron-PTFE test pellets with no additives have a maximum burning rate at fluorine:boron mass ratio of ~ 3.5, which remains the same even with additives at 20 wt%. A commercial fluoropolymer, Aquivion, showed significant burn rate enhancement at 20 wt% but not at 5 wt%. At this lower loading level, materials that tend to enhance thermal conductivity (graphene, nanotubes) show some burn rate enhancement, even without fluorination. However, very significant burn rate enhancement is shown by a fluorinated carbon nanotube, likely due to the reduced bond dissociation energy of fluorine when attached to a nanotube. The data suggest this method of fluorination can have an important effect on enhancing boron combustion, and even small additives with readily available fluorine could significantly improve boron combustion rates for solid propellant applications.

Persulfate catalyst synthesized with waterworks sludge for degrading Safranine T in the presence of boron

ABSTRACT Energy conservation and emission reduction are the general trend of the present world. In this study, a catalyst of 3WSH based on the waste recycle of waterworks sludge (WS) and Chinese herbs was prepared using one-step calcination treatment and then characterized by SEM, XRD, XPS, FTIR and BET. The catalytic performance of 3WSHB for activating potassium persulfate (PDS) was evaluated through the degradation of Safranine T (ST) in the presence of boron powder (B). The effects of vital parameters on ST removal were systematically studied, including PDS concentration, 3WSHB dosage, initial solution pH, B dosage, temperature and coexisting cations. The highest efficiency of ST removal was up to 93.0% under the optimal condition with 1.85 mM of PDS, 0.3 g/L of 3WSHB, 0.35g/L of B, 7 of pH. EPR and free radical quenching experiments demonstrated that •OH was the dominant reactive oxygen species for ST degradation in the PDS/3WSHB/B system. Moreover, the intermediates determined by HPLC-MS indicated that the oxidization of benzene ring substituents in ST and a hydrogen abstraction by electron transfer might occur during ST degradation. The dissatisfied reuse performance of 3WSHB might be attributed to its low Fe content and simple reusing way. The results demonstrate the effectiveness of WS recycling and reuse in the field of pollutant remediation.

Effect of Borophene on the Electrochemical Performances of Li7P3S11 based AllSolid-State Lithium Sulfur Batteries

This study has investigated the effect of 2-dimensional (2D) beta borophene as a cathode additive for all-solid-state lithium-sulfur batteries. The comparisons have been carried out regarding the impact on ionic conductivity based on borophene content. Although the studies of borophene's contributions in the literature on the anode component, this study focuses on the cathode contribution for the first time. While MoS2 has been selected as the cathode active material, carbon black has been selected as the electrical conductor, and Li7P3S11 solid electrolyte has been synthesized as an ionic conductor in all-solid-state lithium-sulfur cells. Borophene has been synthesized from boron powder by the exfoliation method. As a cathodeactive material, MoS2, containing sulfur, and its 2D material nature, eliminates many of the disadvantages that sulfur exhibits when used alone. To investigate the effect of borophene on ionic conductivity in all-solid-state lithium-sulfur cells, multicomponent composite cathodes were prepared in (MoS2 / Conductive Carbon / Li7P3S11 + Borophene) overall compositions. According to the results, the specific capacity of the cells is affected negatively, while the stability of the cell is affected positively when increased the borophene amount.

Numerical investigation on the combustion characteristics of boron powder fuel under H2/Air flame in a supersonic cavity-based combustor

To explore the combustion organization rules of powder-fueled scramjets, this study conducted numerical simulations to investigate the combustion characteristics of boron particles in the supersonic combustion chamber, while varying the injection scheme, cavity structure, and hydrogen flow rate. The results demonstrate that the addition of a small flow of hydrogen assists in the ignition and combustion of boron particles when combined with incoming air in a supersonic combustor. Compared to the injection scheme at the wall of the combustor upstream of the cavity, the proposed intra-cavity injection scheme significantly improves the combustion efficiency of boron particles. Moreover, the combustion efficiency of boron particles improves further as the cavity depth increases. Successful ignition and combustion of boron particles occur when the solid-to-gas ratio (SB/GH) of boron powder fuel to hydrogen is below 20 at a constant boron powder fuel mass flow rate. The highest combustion efficiency of boron particles is observed at an SB/GH ratio of approximately 12.5. Further decreasing SB/GH no longer improves the combustion efficiency of boron particles. The findings of this research can provide valuable insights for the engineering application of combustion organization schemes in powder-fueled scramjets utilizing boron powder as fuel.

Formation a Layered Dissipative Structure in the Process of Directed Growth of an MgB<sub>2</sub> Crystal from a Melt

Abstract—The interaction of components during high-temperature annealing of pressed magnesium and boron powders during the production of the superconducting compound MgB2 is considered in works using standard synthesis technology and hot gas-static pressing technology. In a computer model of crystallization of a binary alloy, the influence of the diffusion of components in the region of the interphase boundary during crystal growth on the morphology of dissipative structures formed during phase transformation was studied. An analysis of the conditions and mechanism of the formation of a “layered” structure that appears during the crystallization of MgB2 from a magnesium melt in the (Mg–B) system has been carried out.

Deuterium recycling and wall retention characteristics during boron powder injection in EAST

Boron (B), as a low-Z material, is widely employed for wall conditioning to enhance plasma performance in fusion devices. In the Experimental Advanced Superconducting Tokamak, a series of experiments involving real-time B powder injection has been conducted to investigate fuel particle behavior. It was observed that fuel particle recycling decreased with an increase in the amount of B powder injected, resulting in an increase in short-term fuel retention. The fuel recycling decreased by up to 80%, as indicated by divertor neutral pressure and Dα line emission. Furthermore, each B atom exhibited a trapping capacity of 0.3 D particles during B powder injection at a typical flow rate. The real-time B injection had no wall hysteresis effect on D retention, implying that cumulative B injection and deposited film did not affect long-term D retention. The possible mechanism for D retention is the formation of B-C-O-D compounds and co-deposition between B and D particles during discharges. This investigation would be valuable for evaluating T retention when B is used as wall conditioning material in future fusion reactor devices.

Electrostatic Spraying Microspheres of Nano Boron and Its Constant-Volume Combustion with Potassium Nitrate

ABSTRACT The nanometer boron (nB) powders have become the most promising high-energy additive in the field of fuel-rich solid propellants due to their extremely high gravimetric and volumetric calorific value. However, further applications are limited by its disadvantages such as easy agglomeration, easy oxidation, high ignition temperature, and incomplete energy release. Herein, nB powders were pre-agglomerated into microspheres by electrostatic spray method using fluoropolymer (F2602) as binders. The morphology and structure of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET). Results showed that the pre-agglomerated nB microspheres had good dispersion, high sphericity, and no surface oxide. The thermal performance and combustion performance of the samples were characterized by a synchronous thermal analyzer and combustion pressure test device. Results showed that the nB microspheres had the highest oxidation weight gain within 1000°C and lowest activation energy compared to the same scale micron boron. In addition, the microspheres significantly shorten the combustion time and improve the combustion efficiency.The pressurization rate of nB microspheres is 4.12 times that of micron boron powders and 2.85 times that of nB powders. These excellent properties may be related to its unique spherical porous structure. Therefore, the preparation of nB microspheres with controllable structure by electrostatic spraying has a good application prospect.

Achieving high heat resistance for phthalonitrile/boron blends through formation of protective phases derived from boron powder

Phthalonitrile resins or its blends with high heat resistance are urgently demanded for spacecrafts that usually operate in extreme environment. Here, the heat resistance of phthalonitrile was significantly improved by introducing boron powders. The boron powders not only played a role in physically insulating oxygen from the matrix but also forming the boron oxide phase, which both retarded the thermal decomposition process of phthalonitrile resin at elevated temperatures. The results show that the as-prepared phthalonitrile/boron blend with 20.0 wt% boron exhibited high Td5% of 549 °C and 552 °C in air and N2 atmosphere, respectively. For the carbon fiber fabric reinforced phthalonitrile/boron composites, the flexural modulus and flexural strength were improved from 82.6 GPa to 778 MPa for phthalonitrile resin composite to 134.2 GPa and 978 MPa at 450 °C, respectively. This work demonstrates an efficient way to prepare phthalonitrile composites with excellent thermal stability and good mechanical performance.

Global gyrokinetic simulations of electrostatic microturbulent transport in LHD stellarator with boron impurity

Global gyrokinetic simulations of electrostatic microturbulent transport for discharge # 166256 of the Large Helical Device stellarator in the presence of boron impurity show the co-existence of the ion temperature gradient (ITG) turbulence and trapped electron mode (TEM) turbulence before and during boron powder injection. ITG turbulence dominates in the core, whereas TEM dominates near the edge, consistent with the experimental observations. Linear TEM frequency increases from ∼80 kHz to ∼100 kHz during boron injection, and ITG frequency decreases from ∼20 kHz to ∼13 kHz, consistent with the experiments. The poloidal wave number spectrum is broad for both ITG (0–0.5 mm−1) and TEM (0–0.25 mm−1). The nonlinear simulations with boron impurity show a reduction in the heat conductivity compared to the case without boron. The comparison of the nonlinear transport before and during boron injection shows that the ion heat transport is substantially reduced in the region where the TEM is dominant. However, the average electron heat transport throughout the radial domain and the average ion heat transport in the region where the ITG is dominant are similar. The simulations with boron show the effective heat conductivity values qualitatively agree with the estimate obtained from the experiment.