Diamond Research Articles

Природные условия Попигайского месторождения алмазов (Северо-Западная Якутия)

The article highlights the features of the diamond mining industry in Yakutia. The history of the discovery andstudy of impact diamonds Popigai deposit formed as a result of the penetration of the eponumous huge meteorite into the rock mass are traced. Some features of Popigai crystals and the prospects of their use in various sectors of the national economy of the country are characterized.

Micro-scale abrasion investigations of single-crystal diamonds using nano-polycrystalline diamond wheels

A small grinding wheel of 3.2 mm in diameter was prepared from nano-polycrystalline diamond (NPD) obtained by direct conversion sintering under high pressure and high temperature. Using this NPD wheel as a grinding blade, a new useful method for investigating the micro-scale abrasive properties of single-crystal diamonds was developed. Since NPD has an extremely high hardness of about 130 GPa, the abrasive properties of various natural and synthetic single-crystal diamonds, whose hardness is usually around 70 to 125 GPa, can be appropriately evaluated. In addition, since the wheel diameter is very small, it is possible to measure the abrasion resistance in a minute region of several tens of μm in a diamond crystal. It was confirmed that the method can accurately evaluate the abrasive properties of minute regions of single-crystal diamonds using synthetic type IIa diamond. It was also demonstrated that it is possible to investigate how the abrasive properties of synthetic type Ib and natural type Ia diamonds change depending on the distribution of impurities or crystal defects in the crystals.

Polarization-dependent near-IR ultrashort-pulse laser ablation of natural diamond surfaces

Single-shot surface ablation of (001) and (111) oriented natural diamond plates was performed by tightly focused (numerical aperture NA = 0.65) 1030 nm 0.3-picosecond laser pulses with variable polarization azimuth. Surface craters were characterized by scanning electron microscopy in terms of characteristic ablation 1/e-radii and threshold fluences. Azimuthal polar dependences of the radii and threshold fluences exhibit distinct patterns, coinciding with specific crystallographic directions and corresponding bandgap widths in the Brillouin zone, and implying multiphoton-excitation seeding process. For comparison, anti-correlating azimuthal dependences were also observed in the bulk diamond for side-viewed A-band photoluminescence yield and forward non-linear transmittance.

Effect of Tool Geometry and Turning Parameters on Cutting Force during Ultra-Precision Diamond Machining of Rapidly Solidified Aluminum (RSA) Alloy 6061

The most important goal of advanced diamond machining is to improve precision and product integrity. Cutting force could have a strong effect on diamond machining performance and hence, it can be used as an indicator for monitoring tool condition for achieving successful machining. Moreover, diamond machining process parameters such as cutting speed, depth of cut and feed rate may strongly influence the process outcomes in terms of surface roughness and tool failure. Diamond machining parameters have a significant role on the cutting force values, and machine-tool stability during ultra-high precision machining that makes use of a natural diamond cutting tool. The main objective of this research work is to investigate the effect of cutting speed, feed rate, depth of cut and nose radius on the cutting force generated during diamond turning of a rapidly solidified aluminum alloy grade called RSA 6061. The effect of nose radius and cutting parameters on cutting force during the ultra-high precision diamond turning process was monitored. The study shows that low speed, low depth of cut and an increase in feed rate at large nose radius consequently results in increase in the cutting force.

Evaluation of surface treatments by self glaze, over glaze and a polishing agent on the porcelain surface modified with diamond rotary instrument-an in vitro study

The purpose of this study is to evaluate effect of a) Self glaze b) Over glaze and c) Polishing on porcelain surface which is subjected to grinding with a diamond rotary instrument. To test this theory 40 ceramic fused to metal disc samples were fabricated. The ceramic material used was Ivoclar Dsign. The discs were of 10mm X 3mm of which 2mm is metal substructure and 1mm is of porcelain. The specimens were divided into four groups of 10 samples each. The first group was left as fired or unglazed. The remaining three groups were subjected to surface modification with sintered diamond bur at 15000 rpm per minute with even pressure. Each of the three groups was treated with diamond polishing paste, self glaze and overglaze respectively. The surface of all the four groups were evaluated under optical microscope and scanning electron microscope. Optical microscope observation revealed that Group-I (as fired) had the surface of the specimens appearing to be pitted, rough with irregularities and there was no evidence of surface cracks. Group II (polished with diamond bur) had surface appeared to be very smooth.

Morphology and FTIR Characteristics of the Alluvial Diamond from the Yangtze Craton, China

A total of 48 natural alluvial diamonds from the Yangtze Craton, China, also called Hunan diamonds, were studied using morphology and IR spectroscopy. These diamond samples, collected downstream of the Yuan River, Hunan Province, with unknown host-rock source(s), were observed by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR). Most Hunan diamonds are monocrystal forms of octahedra, tetrahexahedra (THH) and dodecahedra; octahedral–rhom-dodecahedral transitional behaviors and irregular forms are also visible. Trigons and tetragons, terraces and shield-shaped laminae are surface features that frequently indicate dissolution and reabsorption; green and brown spots, network patterns, and other mechanical abrasion marks are typical evidence of long-time deposition and transportation of Hunan diamonds. The main types of Hunan diamonds are type IaAB and type Ⅱa. Diamond samples have a wide range of total nitrogen content (Ntot) from 196–1094 ppm. Two populations are distinguished by two-peak distribution models of NA (A-center concentrations) and %B (proportion of aggregated nitrogen). Hunan diamonds are low in structure hydrogen (0.03–4.67 cm−1, mostly below 1 cm−1) and platelets (0.23–17 cm−1, mostly below 2 cm−1). Moreover, there is a significant positive correlation between the hydrogen correlation peak and Ntot, which is similar to Argyle diamonds. The temperature conditions of the diamond formation have been estimated at 1075–1180 °C, mainly conforming to the kimberlite diamond range. Besides, some samples with slightly higher temperatures are close to the ultramafic-related Juina diamonds. Therefore, the FTIR characteristics analysis and comparison indicate the multiple sources of Hunan diamonds.

Editorial

Editorial

Orientational Dependences of Diamonds Grown in the NiMnCo–Silicate–H2O–C System under HPHT Conditions and Implications to Natural Diamonds

Orientational Dependences of Diamonds Grown in the NiMnCo–Silicate–H₂O–C System under HPHT Conditions and Implications to Natural Diamonds

Operation Parasite: diamonds, smallpox, and mass expulsions of strangers in colonial Sierra Leone

ABSTRACT In 1956, the British colonial administrators in Sierra Leone organized an operation of mass expulsion of migrants that aimed to solve the problems of health and security in the country’s diamond mining areas: Operation Parasite. This article examines how colonizers created artificial categories of “strangers” to expel people who were legally designated “undesirable subjects,” as well as how the health conditions of those living in the mining villages together with an ongoing epidemic of smallpox were instrumental in morally justifying this operation. The article argues that Operation Parasite was not only a police operation used to expel migrants to protect the interests of mining capitalism, but also a medical operation, which contributed to establishing the representation of an inverted reality: namely, that migrants, not colonizers, were the exploiters of Sierra Leone’s natural resources.

Experimental Modeling of Diamond Resorption during Mantle Metasomatism

The morphology of resorbed diamond crystals is a valuable source of information on the composition and ascent rate of kimberlite magmas, as well as on possible redox conditions in protolith. Previously, diamond resorption was thoroughly investigated at P–T–fO2 parameters of the kimberlite magma ascent. In this study, we investigated diamond resorption using unaltered group I kimberlite and model carbonatite at P–T–fO2 parameters that are typical of the peridotite source of kimberlite magmas in the subcontinental lithospheric mantle. An analysis of previous studies made it possible to determine the rate of diamond octahedron transformation into a spherical tetrahexahedron depending on the composition of the carbonate–silicate melt. It was shown that the rate of diamond resorption at 6.3 GPa increases in all the investigated systems as fO2 and temperature rise. There is a steady decrease in the diamond resorption rate as pressure increases from 1 GPa to 6.3 GPa. The morphology comparison of the experimentally produced samples with natural diamonds is indicative of the significant contribution of metasomatic alteration of protolith by the oxidized agent and at the initial stages of kimberlite magma ascent to the resorption of natural diamonds.

Visible-light catalyzed assisted chemical mechanical polishing of single crystal diamond

The high hardness, wear resistance and chemical inertness of single crystal diamond makes it challenging to achieve high efficiency and high quality chemical mechanical polishing (CMP) of single crystal diamond with material removal rate MRR higher than 300 nm/h and surface roughness Ra lower than 0.5 nm. The hydroxyl radicals (·OH) produced by the Fenton reaction are strongly oxidizing and can be used for CMP. In this study, ND/LDH catalysts synthesized from nanodiamond (ND) and CuFe-layered double hydroxide (LDH) for visible-light-Fenton reaction were prepared. The dynamics of the ·OH concentration produced by 4 groups of reaction solutions, including hydrogen peroxide and hydrogen peroxide mixed with ferrous sulfate and hydrogen peroxide mixed with ND/LDH and hydrogen peroxide mixed with ND/LDH (visible-light irradiation), were measured. Then, the single crystal diamond was polished with 4 groups of reaction solutions with diamond powder added. The results showed that: hydrogen peroxide mixed with ND/LDH (visible-light irradiation) reaction solution produced the highest ·OH concentration, and achieved high efficiency and high quality polishing of single crystal diamond, with the material removal rate MRR of 370 nm/h and surface roughness Ra of 0.110 nm.

Color Genesis of Brown Diamond from the Mengyin Kimberlite, China

The Mengyin diamondiferous kimberlite cluster in Shandong province is one of the three major sources of natural diamond in China, where many brown diamonds are mined, but the genesis of their color is still controversial. In this paper, studies including microscopic examination, optical properties of orthogonal polarization, low temperature photoluminescence spectra, infrared spectra, Raman spectra, ultraviolet-visible absorption spectra, luminescence of cathodoluminescence, and transmission electron microscopy have been carried out on the uncut brown diamonds and their slice samples to constrain on the color genesis of brown diamond from the Mengyin deposit. The results show that the brown color is dominantly caused by plastic deformation, and some samples are also caused by non-deformation-related defects and inclusions.

Influence of treatment on rooting of arctic Salix species cuttings for revegetation

ABSTRACT Increased northern exploration and resource extraction highlight a need for effective revegetation techniques to restore disturbed environments. This study assessed effects of indole-3-butyric acid (IBA), water extracts of Salix and smoke, soaking time, and collection time on adventitious and lateral root development of Salix species cuttings collected from Diavik Diamond Mine Inc., Northwest Territories. Over 80 percent of fall and spring cuttings developed adventitious roots, yet only 30 percent of summer cuttings rooted, indicating strong seasonal influences. Many cuttings developed extensive root system architecture in 60 days; some developed up to six orders of roots. Root length decreased with increasing root order in all seasons, and season influenced length within root orders. Application of IBA increased number of primary roots per cutting per season and number of cuttings with less than fifty secondary roots per primary root. Longer soaking times increased number of primary roots per cutting in different seasons, and soaking up to ten days increased longest root length. Salix and smoke water extract applications increased number of cuttings with twenty-five to seventy-four secondary roots. This research highlights the importance of treatment effects on adventitious and lateral root development to optimize root system architecture of cuttings from northern shrub species.

A Review of Binderless Polycrystalline Diamonds: Focus on the High-Pressure-High-Temperature Sintering Process.

Nowadays, synthetic diamonds are easy to fabricate industrially, and a wide range of methods were developed during the last century. Among them, the high-pressure–high-temperature (HP–HT) process is the most used to prepare diamond compacts for cutting or drilling applications. However, these diamond compacts contain binder, limiting their mechanical and optical properties and their substantial uses. Binderless diamond compacts were synthesized more recently, and important developments were made to optimize the P–T conditions of sintering. Resulting sintered compacts had mechanical and optical properties at least equivalent to that of natural single crystal and higher than that of binder-containing sintered compacts, offering a huge potential market. However, pressure–temperature (P–T) conditions to sinter such bodies remain too high for an industrial transfer, making this the next challenge to be accomplished. This review gives an overview of natural diamond formation and the main experimental techniques that are used to synthesize and/or sinter diamond powders and compact objects. The focus of this review is the HP–HT process, especially for the synthesis and sintering of binderless diamonds. P–T conditions of the formation and exceptional properties of such objects are discussed and compared with classic binder-diamonds objects and with natural single-crystal diamonds. Finally, the question of an industrial transfer is asked and outlooks related to this are proposed.

Обоснование оптимального уклона крутонаклонных автосъездов для полноприводных автосамосвалов, эксплуатируемых при доработке алмазорудных месторождений

At present, the design depth of open-cast diamond (kimberlite) mines is increasing through introduction of advanced technologies and new mining and transportation equipment. In 2008-2012 the Yakutniproalmaz Institute and the Institute of Mining developed scientific and methodological principles and design solutions for development of the Udachny and Botuobinsky deep open pit mines using steeply inclined ramps and the CAT-740B articulated dump trucks with the capacity of 39.5 tons. Research was conducted to determine the rational slope for articulated dump trucks in the Udachny open pit and to develop guidelines for safe operation of such dump trucks on steep inclines. The performed experiments demonstrated the ability of articulated dump trucks to safely haul rocks with loads that were close to the nominal capacity using ramps with the slope gradients up to 24% in various weather conditions. In spite of a sufficiently large number of studies on justification of parameters of developing deep open pit levels, many questions still require additional research. This is primarily explained by the limited experience of operating articulated dump trucks in Russian deep open pit mines. In this context, the issue of justifying the optimal slope gradients for all-wheel drive models of motor vehicles remains relevant. The authors of the article have analyzed the existing normative documents and methods to determine the rate of longitudinal slopes. As the result of the study, the physical criterion of the least action is proposed as the optimization criterion for the slope gradients of the in-pit roads when operating all-wheel drive dump trucks.

A Comparative Study on Simulated Chairside Grinding and Polishing of Monolithic Zirconia.

This study evaluated the effects of different simulated chairside grinding and polishing protocols on the physical and mechanical properties of surface roughness, hardness, and flexural strength of monolithic zirconia. Sintered monolithic zirconia specimens (15 mm × 3 mm × 3 mm) were abraded using three different burs: diamond bur, modified diamond bur (zirconia specified), and tungsten carbide bur, along with a group of unprepared specimens that served as a control group. The study was divided into two phases, Phase 1 and Phase 2. Surface roughness, surface hardness, and flexural strength were assessed before and after the grinding procedure to determine the ‘best test group’ in Phase 1. The best abrasive agent was selected for Phase 2 of the study. The specimens in Phase 2 underwent grinding with the best abrasive agent selected. Following the grinding, the specimens were then polished using commercially available diamond polishing paste, a porcelain polishing kit, and an indigenously developed low-temperature sintered zirconia slurry. The physical and mechanical properties were again assessed. Results were analyzed using one-way ANOVA test. Specimens were observed under scanning electron microscopy (SEM) and X-ray diffraction (XRD) for their microstructure and crystalline phases, respectively. Grinding with diamond burs did not weaken zirconia (p > 0.05) but produced rougher surfaces than the control group (p < 0.05). Tungsten carbide burs did not significantly roughen the zirconia surface. However, specimens ground by tungsten carbide burs had a significantly reduced mean flexural strength (p < 0.05) and SEM revealed fine surface cracks. Phase transformation was not detected by XRD. Polishing with commercially available polishing agents, however, restored the surface roughness levels to the control group. Dental monolithic zirconia ground with tungsten carbide burs had a significantly reduced flexural strength and a smooth but defective surface. However, grinding with diamond burs roughened the zirconia surface. These defects may be reduced by polishing with commercially available polishing agents. The use of tungsten carbide burs for grinding dental zirconia should not be advocated. Grinding with diamond abrasives does not weaken zirconia but requires further polishing with commercially available polishing agents.

Polished diamond X-ray lenses.

High-quality bi-concave 2D focusing diamond X-ray lenses of apex-radius R = 100 µm produced via laser-ablation and improved via mechanical polishing are presented here. Both for polished and unpolished individual lenses and for stacks of ten lenses, the remaining figure errors determined using X-ray speckle tracking are shown and these results are compared with those of commercial R = 50 µm beryllium lenses that have similar focusing strength and physical aperture. For two stacks of ten diamond lenses (polished and unpolished) and a stack of eleven beryllium lenses, this paper presents measured 2D beam profiles out of focus and wire scans to obtain the beam size in the focal plane. These results are complemented with small-angle X-ray scattering (SAXS) measurements of a polished and an unpolished diamond lens. Again, this is compared with the SAXS of a beryllium lens. The polished X-ray lenses show similar figure errors to commercially available beryllium lenses. While the beam size in the focal plane is comparable to that of the beryllium lenses, the SAXS signal of the polished diamond lenses is considerably lower.

Measuring the effectiveness of corporate social responsibility initiatives in diamond mining areas of Sierra Leone

Although some scholarly attention has been given to assessing the effectiveness of corporate social responsibility (CSR) in the mining industry, this study provides a comprehensive assessment of the effectiveness of the economic, social, and environmental dimensions of CSR initiatives towards the development of diamond mining communities in Sierra Leone. It utilizes a CSR framework that encompasses a social license to operate (SLO), accountability and community engagement. Household survey, key informant interviews, and secondary sources provided data for the study. The results indicate that the degree of effectiveness of the three dimensions of CSR towards meaningful development in the mining communities were generally low. The economic dimension of CSR was the highest (54%), followed by the social dimensions (48%), while environmental effectiveness was the lowest (27%). Lack of active community involvement in the planning and implementation of CSR programs and local political structures undermine the effectiveness of CSR initiatives in host communities. Moreover, the study reveals that extant CSR approaches are not the most optimal in ensuring meaningful development of mining communities as they are for the most part not community-driven. The study also demonstrates that even though the industrial mining company maintains its SLO through laudable ventures such as road maintenance, allowing women to engage in stone mining, and constructing a health care center, its recent handling of educational support was questionable. Furthermore, company-led development projects may not always be the priority needs of diverse groups within the host communities. The study calls for community-driven CSR in the true sense (including representatives of youth, women, elders, disabled, civil society) not just the views of powerful and influential traditional leaders.

“A flaw in the great diamond of the world”: Reflections on subjectivity and the enterprise of psychology (A diptych).

“A flaw in the great diamond of the world”: Reflections on subjectivity and the enterprise of psychology (A diptych).

A Historical Perspective of Diamond Mine Dewatering Design and Guidelines for a Modern Diamond Mine

A Historical Perspective of Diamond Mine Dewatering Design and Guidelines for a Modern Diamond Mine